In many European countries, including France where I'm from, there are never any political ads until an election season (which could either be tradition or regulation). During election season political ads are tightly regulated to prevent someone with a higher ad budget from swarming the "airwaves" with the kinds of disinformation/propaganda that is so prevalent on U.S. television networks and other media.

Political ads (and statistical coverage of early poll results) is also banned in the days before a major election to diminish the impact of manipulation/disinformation campaigns (discouraging voters because they assume their vote won't matter).