Because in B2B nobody is intrested on VAT. VAT is an pass through position. On all B2B web-shops I know, you get shown prices excluding VAT on the product listing and for the accounting you get prices incl. VAT. In other case the calculated prices for the paymentsystem are wrong. It's partially correct to say " .. there is a EU law that says that all the e-commerce websites must show the price including VAT in every page.", but only for consumer-prices (B2C).