We all know that governments never do anything just for its own sake. They like to “send a message”. It might be about smoking, fatness, booze, driving, community - they've gotta send it. We can't be trusted to know how to behave (unlike ministers, who have no vices). So messages are sent.

In Budget week they come thick and fast. Don't drink, shun plastic bags, recycle, drive less. But there is a core message, an important one, directed ever more stridently at the poorest people in Britain and designed to deny hope and resourcefulness. If you are poor, the Government's message is simple: “You are not in charge of your life and prosperity. We are. Trust us. Keep on voting for us or you're stuffed.”

The means by which the message is transmitted is the creaking tax and benefit system. Looming changes in income tax mean that those earning more than £18,500 a year, which is lowish but not too uncomfortable, will be better off when the basic tax rate drops by 2 per cent. But given the abolition of the 10 per cent tax rate, coupled with the continuing feebleness of the personal allowance (you can earn £104.51 a week before you start paying a fifth of it to the exchequer - whoopee!), the lowest earners are hit. Those on £10,000 a year will now pay two or three quid a week more in tax. However, says the message, that's OK because they can promptly apply for “working tax credits”, “family credits” and other benefits.

However doughtily and responsibly you work for your 200 quid a week, even if you need every penny of it to survive, the Government will make you hand over a lump and then give it back, ceremoniously, via its huge and expensive bureaucracy. The message is that if you are poor, you must be kept in the status of client and petitioner. It would presumably save billions in administration if you just let low earners hang on to their wages; it would also fortify that sense of personal and family responsibility that government claims to like. Applying for state benefits as a fit person of working age makes everyone feel lousy, unless - or until - they are so desensitised and deprived of pride that they no longer care. But the abolition of the low tax band and the feeble personal allowance has made benefit-claiming inevitable for more people, for longer.

In the financial-Sunday-section jungle I noticed something else. It was a warning to buy-to-let landlords with tenants on housing benefit. They are usually paid directly, the money bypassing the tenant's pocket. Now an experiment is being run in nine authorities in which the tenant handles the rent money. Cries of dismay from landlords: “We envisage some, used to surviving on £55 per week... being tempted to use the funds for other purposes.”

The author cites problems in Blackpool where “insiders are blaming the scheme for intensifying the local drink and drugs problem”. Another difficulty is that many would-be responsible tenants still can't find a “basic bank account” if there is the slightest irregularity in their desperate past. Meanwhile, the effect of this small attempt to trust individuals is, the piece says, panicking landlords in deprived areas into selling and making property prices fall. Well, hoorah; why should poorer people pay your mortgage while you watch your investment soar? Let housing associations buy them.

But to me the mystery is that for so long we have happily lived with this presumption that the poorer you are, the less you are to be trusted handling money. Which can only be a self-fulfilling prophecy. Housing benefit - in this expensive country - is a necessity for many. But being expected to conserve and ring-fence the rent yourself has to be better than being babied by the pretence that your rent is not your business. In the same way it is better to keep your own proud earnings - right up to a liveable level - than to hand chunks over and immediately beg nanny government to give them back.

Designers of welfare may contest all this as impractical, romantic, a recipe for chaos. They hug their barely hidden assumption that if you are poor you are ipso facto feckless: drugged, drunk, dumb or spendthrift. A few indeed are, and need special treatment. But in the wider human context the opposite has generally proved true. The poor are not feckless by nature, but careful. Ask any of the vastly successful organisations that offer “microcredit” in developing countries. They lend tiny sums to families, often women, to start businesses; they charge stiff interest yet their repayment record is extraordinarily high - better than many mainstream banks. History and anthropology do not throw up many examples of poor people wasting money. If we have indeed grown a feckless, helpless client population who can't be trusted, it is state messages that have made them that way.

We hear a great deal about the perils of taxing rich “non-doms”, these weird creatures who may abandon London if asked to pay a bit more tax, having apparently chosen Britain as their home not out of affection or friendship but just to save a few quid of disposable income. It is wrong, say the experts, to send the poor non-doms the “message” that they aren't loved.

In which case, why is it right to send poor Britons the message that they can't trust themselves but only the State? Alistair Darling could ramp up the personal allowance, make it transferable and turn his mind to ways of letting people keep earnings rather than claim benefits. Pigs could fly.

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