I don't think businesses really like ads. Businesses are forced to buy ads. On Facebook if you want to reach your entire audience you need to pay them, they gate off people seeing content they're subscribed to unless you pay. Google is terrible at surfacing relevant local events.
Ads are forced on small business because regular methods of discovery are intentionally nerfed.
Putting a flyer on a community board or telephone pole. My city has special poles just for flyers.
Word of mouth.
Newspaper ads.
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Sure, some of those are advertising but they're not intrusive or unethical. There aren't as many options for ethically advertising online but that's very intentional, with companies doing the digital equivalent of limiting word of mouth and tearing down flyers.
Ads are forced on small business because regular methods of discovery are intentionally nerfed.