[killedbydeath]

You can go really deep down the rabbit hole of seat knowledge with Seatguru, but it's quite time consuming. Their flight search is reasonable, and probably many people who care about seats do use them. But the majority probably does not even suspect that there are major differences in seat sizes between airlines and even planes. So having that information more visible across the board would change incentives more. I also suspect given how many booking sites make money they would be dis-incentivized to do this on their own.