New Yorkers have just witnessed the second case of one of the local mega-businessmen being hauled off in handcuffs for evading sales taxes on art purchased in the city. The culprit this time is Samuel Waksal, who may yet go down in glory for his role in finding a cure for cancer but may well have to spend time before then stewing in the big house. Last year it was Dennis Koslowski. The prosecutors seem to be suggesting there may yet be more cases.

We have the impression that avoiding sales taxes on art bought here — or use taxes on art bought elsewhere and brought into the city — has been something of a parlor game among the rich for decades. It’s a good thing to see it being brought to an end. Lying, phonying documents, claiming art is going to a destination where it isn’t going to be used, these kinds of fraud are no less immoral for the fact that the underlying law is burden some and illogical.

But the burden of excise is something to think about. In the spectacle of Koslowski and Waksal, the city sees what even rich people are willing to risk to escape these levies. Imagine the burden that is felt by ordinary wage-earners and persons on fixed incomes. For excise is one of the most regressive of taxes, meaning it bears down on the poor more painfully than on the rich. And there’s little doubt that avoiding the excise of sales and use taxes is a practice followed by plenty of ordinary New Yorkers.

They pay home-improvement contractors or others in cash instead of checks. They buy clothing from street venders, who don’t col lect the tax, instead of from storefront shops that do. They shop at factory-outlet malls while vacationing in low-tax states, then bring the clothes or other merchandise back into New York City. They order books online from Amazon.com or clothing from the L.L. Bean catalog. These actions may fall into gray areas; some are certainly less flagrant than Waksal’s offense.

But even plainly illegal sales tax avoidance and evasion by ordinary New Yorkers is rarely prosecuted. It isn’t accompanied by the kind of press coverage that the Waksal case has brought. There was a famous exception some years ago, when the State of New York tax snoops sent warning notices to shoppers whose license plate numbers they’d spotted shopping at an Ikea in New Jersey. Howls of protest went up and the gumshoes backed off.

So what is left is a regressive excise structure and what might be called “progressive enforcement,” in which the prosecutors go after the big fish whose tax bills are enough to make it worth their time, while letting the little guys off scot-free. We already have a system of progressive taxation on incomes in this country that, in its excesses, produces perverse incentives and punishes the most successful Americans.

No one here or elsewhere sheds a tear when rich lawbreakers are led away in handcuffs. But if laws that apply to us all are enforced only against the rich — if to try a similar enforcement against ordinary New Yorkers would produce an instant backlash — then maybe it’s time to rethink the logic of the excise system in the first place and focus on the kind of flat taxes on income that could be enforced against all.