Location: Pennsylvania
I used a font on a non-commercial website with very little traffic (<20 per month) for a research project. The font has been update fro maybe 2 years now.
Font Radar, an enforcement company working for the font's owner, emailed me asking for a license. I said I'd remove the font. They replied that removing it doesn't fix the past use and sent a $300 license link.
I'm removing the font either way. If I don't pay, what's my realistic risk? I don't have $300 I can spend. I got the font online from the first sight I saw. Sure, it wasn't the most prudent thing to do, but I also wasn't trying to actively pirate the font.
Edit: I’m 99% sure this company is not a scam and is legitimate.