Ah, but see that would require actual human attention and judgment for the vetting process, which would cost money. Automating the ad selling process is so much better… for the shareholders.
Hmm, sarcasm aside, now I’m thinking about it and wondering if you could at least automatically scan the ad content and distinguish between say, a jpg or webp image and a potentially malicious executable. If you could prevent ads from running any code, and only allow them to display static images, that might be good enough.