Just give them your ad code (a JS snippet), this way you control your ads.
Billing is a solved problem too, no?
Billing is a solved problem too, no?
No. Billing is a huge pain in the ass. Negotiating price with each site is a huge pain in the ass. Building a reliable JS snippet that works everywhere and that these sites will trust is also a huge pain in the ass. Everything about dealing with 5k sites manually is a pain in the ass, which is why ad networks exist in the first place.