[belorn]

Lets look at other media and see if your conclusion is correct. Do TV networks vet, produce and handle the ad-client and ad-publisher relationship, or do they mainly interact through marketing firms? The answer: they work mainly through marketing firms. The TV network is still ultimately responsible for the content they broadcast, as dictated by law.

Do newspaper work with individual advertisers, or do they work mostly through local marketing firms? The answer is again the same as above. Buying a news ad is commonly done through a marketing firm and the news paper is always responsible for what is printed.

Very few publisher in any media deals with individual advertise clients, and yet it works. Responsibility is done through contracts, through professional liability and standards, and as last resort through business insurance. As a result, its quite uncommon to see illegal ads on physical newspapers, on TV, on busses, and on other physical objects.

[tempestn]

Are you sure there aren't scams advertised in newspapers and on TV? The main reason you see more scams online though isn't (only) because of inferior vetting. It's mostly because online ads are much cheaper than TV, so the economics work out better for the scammers. Same reason you get more spam in your inbox than your mailbox. (And there are plenty of shady classified ads in newspapers. You probably don't see them because like most of us, you don't read newspapers.)

Now, they do also do more manual vetting, but they can afford to, because again, the ads cost more. Maybe online ads need to cost more too. It just means that some fraction of the current legitimate advertisers will no longer have sustainable business models.

[belorn]

In Sweden where i live, a TV station that would repeatably broadcast illegal ads would loose their license. They would not be allowed to use the radio frequencies, and would loose millions from such outcome. When government agency that deal with TV broadcast makes a decision, or the consumer protection agency (a other government branch), they do listen.

Almost a decade ago, ads about subscription services went through a major change. The government dislike how "free" was used in services where all the costs was hidden in the fine print. As such, all ads related to subscriptions was changed so the the total price must be very explicit in the ad. The TV, news papers and street advertisement immediately changed as a result, mostly by stopping having advertisement for such services. They were afterward put back once marketing firms learned how to stay compliant with the decision.

Even further back in history there was a ruling against advertisement that targeted children, where there was one particular channel that went a bit further than everyone else. After the ruling, they stopped.

Now, one could assume that the sword is only dangling above the TV networks and the news papers are running wild with scamming advertisement. Except that I can find rulings (by the consumer protection agency) that target advertisement in print. A ruling in 2003 made a decision against a home catalog, ordering the company to stop printing a style of advertisement (about weight control) or face a fine of $40000 per issue.

Sweden don't have much general classified ads in newspapers, so I guess that might answer why I don't see so many shady versions. Jobs ads are done through the government job agency, and selling things through newspapers tend to be quite expensive so its almost exclusively about cars, boats or houses. Criminals tend to target cheap alternatives so that a failed attempt has less of a sunk cost, which means those who has no vetting process and minimal investment.