> Why would there be any significant added cost to consumer good pricing?

Assuming ad tech makes advertising more effective, banning it would make challenging a market incumbent more difficult. You'd need to burn more cash to teach more consumers about your product, a larger fraction of whom would be outside your target market.

Granted, ad tech does not always add value. And there is a legitimate question as to the trade-off between privacy and consumer prices. But the tradeoff exists. Reducing the threat of new entrants means incumbents will raise prices.