do TV broadcasts provide localized advertisements by altering the TV photo
What a great idea -- you should enter the marketing field!

I don't know if anyone has thought to do localized advertisements yet, but image post-processing is routinely used, at least on American football broadcasts, to track the field and the marker lines thereupon, so as to provide various forms of in-game analysis.

If they can do that, I'm sure they could turn the field-side displays into green screen to show localized TV advertisements on, but if that happens, then the spectators at the physical location aren't able to see the advertisements! So some of this probably has to do with whether it's the TV station or the Stadium that sells those ads, and whether or not localized broadcast ad revenue would be more lucrative than installed non-processed ads.