The only thing is that Amazon is more diversified than other retailers, in particular, they have AWS, essentially selling the platform that runs their website to third parties. It makes sense for them to offer sell their ad service to third parties too.
B&M is different, Ads are there, but you aren't forced to look at them like Amazon does.
Ignorance is bliss. Unfortunately, even your physical Walmart store is also selling a lot of shelf space to manufacturers/advertisers (similar to how Amazon sell the first slot, or at this point first 'page'), especially those checkout lines (https://www.cbsnews.com/news/how-grocers-wring-extra-cash-ou...). That's why your on-boots retail staff can't change those planograms (which defines how to layout shelf space in a grocery store) willy-nilly, they're designed by the highest bidder. That's why those soda or chips seems placed in too convenient slots that are also 'coincidental' to those currently advertised in other ways, because it's, plain and simply, paid to be there.
To be clear, it's gross, but they are doing it just enough that their convenience and average sufficient product quality keeps me using them. I'd guess they do a lot of research to keep that balance where it is.
In many ways this is symptomatic of larger trends in society and managerial culture of looking for ways to measure things rather than confronting the messy subjective non-measurable reality.
The only time we'll get a true counterfactual is when a competitor arises who can meet Amazon's very high bar for logistic excellence but can offer a more appealing interaction, and then Amazon retail will die off without anyone understanding how or why it happened.
But I'm close. My purchases through them are down probably somewhere around 80%. My girlfriend never really used Amazon and doesn't see the appeal at all - telling someone "it used to be good" makes you wonder what you're doing.
Even AWS has burned me and clients enough times that we pretty much don't use them anymore - an idea that was unthinkable a decade ago.
The other thing is that the more they burn this goodwill the more they'll be tempted to increase ad revenue, and the more the goodwill will disappear.