> Embed the ad in the content.

You're then asking businesses to pay to place ads that you cannot assure them were actually viewed by anyone. It can work, but companies will pay more for ads that can prove they were even rendered let alone uniquely.

Many business models don't work with reduced revenues, thus you can embed ads in content, take the lower revenue, but then need to structure your business around the lower total revenue.

Typically, when businesses have goals like these they end up instead just doing a membership model wherein it is ad-less but the users/audience is paying them directly for content production.

If the ad is an image and it’s been fetched from the server then it’s reasonable to assume it’s been viewed no?

Generally no, as botnets can and do trivially spoof that kind of activity to burn competitors ad budgets or generate more revenue for the ad networks or websites.