They may not immediately call up the radio station to complain about it, but if AI-generated commercials are off-putting enough to cause listeners to avoid that product or service, the advertiser will see a lower return on their ads, and may simply stop advertising on radio, eventually hurting the radio station.
Plus, even the best AI voices I've heard, with no obvious signs like awkward pacing and stilted emphasis, generally sound bored and disinterested in whatever they're talking about. That's maybe fine for underwriting announcements on public radio, but when you're trying to sell something, the passion just isn't there, and it is noticeable.