Casual dining establishment TGI Fridays, you may have heard, is advertising what it bills as “endless” appetizers for a mere $10. Yet if you dine at Fridays here in the District of Columbia, you can expect to spend $11, not $10, on the “endless apps,” once DC’s 10 percent dining tax is included. (Nor are the medical bills incurred from eating endless TGI Fridays appetizers included in the $10 figure.) The extra $1 on the tab, I would imagine, come to the surprise of precisely zero diners. People have long grown accustomed to adding taxes to advertised prices.

Likewise, when the local electronics store—assuming it still exists—advertises the low, low prices on its laptops, people are well aware that they’ll end up paying more after taxes are tacked on. “$699!” the ad may blare, but people know that they’ll likely end up spending in the $750 range for that Dell Inspiron (unless they’re lucky enough to live in Oregon, Montana, or another state without a sales tax, that is).