I used to work in this field (verifying local business listings). Locksmiths are traditionally the spammiest and scammiest industry of them all (along with taxis, before rideshare cut down their ROI). Basically any service area business has huge incentive to spam any and all business listing providers, and for whatever reason the locksmith industry became the worst of them. Flower delivery and personal injury lawyers often fall into the same bucket. You'll still see companies named "AAA Locksmith" and the like because this behavior dates back to the days of the Yellow Pages.

As to why Yelp is better than Google on this, I'd guess it's either that you got lucky, or that Google is more targeted than Yelp these days. I'm not up on the current state of how listing verification works now, but it's possible that Google's process is easier to target than Yelp's, and if there are any weaknesses, a locksmith marketer will figure it out pretty quickly.