It’s really depends on the scam, but some of them really do pick a random person. Or, rather the autodialer/autotexter that they are using does. I’ve gotten several scam texts in the last week fishing for info.

Further, there is a lot of into out on the web. Some is just an easy look up for name and adddres from a phone number, other data is pulled from breaches that ends up public or for sale.