Why is today's trackside advertising so bland today?
Not long ago (the 2000s, and especially the 90s) trackside advertising was a big part of how colorful and vivid the sport used to be. It just felt right to see Fuji TV advertising for the Japanese GP, Fosters for the Australian GP, Air Canada for the Canadian GP, Sinopec for the Chinese GP, etc, etc. Now all the tracks look basically the same, with largely the same sponsors (or sometimes a worrying lack of).
Have the rules for trackside advertising changed? Does it hurt the finances of the tracks (the chances of hosting a GP) not to be able to have a local sponsor?