Just to verify--as I truly do have a contempt for big tech oligopoly that extract rent from everyone to do anything at all, but am just unsure this specific problem is a ramification of such--are you sure you would not have had a large advertising budget pre-Google, or even pre-Internet? You used to pay to pay for limited space in newspapers and limited time on TV/radio stations, which also had high theoretical per-unit margins, or for a massive pile of physical mailers and door hangers, along with the cost of the delivery.

To the extent to which our current situation costs more, I'd think it might merely be because of increased worldwide competition: it used to be that the people trying to advertise to any specific random community were also likely local, and probably had a legit attempt at a business model... only, now, the rise of online companies funded by speculative venture capital means that an attempt to advertise a restaurant to people who live in a 10 mile radius must compete against a company that raised $400m to sell an online engagement platform that cares not one iota who uses it as long as the conversion cost is cheap, bidding up ads everywhere.

(One place that does seem to me to be uniquely the fault of these modern tech companies, though, is that if a newspaper published a scam ad, whether or not they had legal culpability, I think they and their surrounding community did at least strongly feel that they had some level of moral culpability. In the current tech environment, people seem to want to believe Meta/Google should be allowed to indiscriminately publish ads from bad actors, so you now must also compete to bid for limited attention with obvious-to-most-but-not-all scams and grifts that make money out of nothing but bullshit and are thereby willing to again bid up prices anywhere and everywhere.)