As a counter data point, I fairly enjoy alerts like these. Whether you like them or not is quite subjective. If it was a really serious distracted driving issue, then the entire billboard industry likely wouldn't exist.
Billboards next to highways are illegal in many countries.
That's for aesthetic reasons though.
Maybe. But it also seriously helps to avoid being distracted. I live in Seattle and drive to my parents house in Vegas, almost always driving I-90 -> I-82 -> I-84 -> I-15. Washington is great. Hardly any billboards. Oregon and Idaho are about the same. Driving through Utah is awful. Billboards everywhere some of them are brightly lit and flashing. I feel much more distracted by them.