Taxing times at the BBC

A sales tax is a consumption tax charged at the point of purchase for certain goods and services.

Value added tax (VAT) is similar to a sales tax. It is a tax on the estimated market value added to a product or material at each stage of its manufacture or distribution, ultimately passed on to the consumer.

So says Wikipedia, but ‘similar to’ does not mean ‘the same as’. There is a crucial difference. Sales tax is only charged at the point of purchase, while VAT is charged at each stage of the production/commercial process. Why does the BBC say one when it means the other? Who knows?