Sorry but what the fuck are you planning to do with 50,000 driver's license numbers?
Well, two people are very interested in that, one can find out, and the fourth can exert some leverage and get at information.
The first two are your DMV (or other agency) and insurance company. The DMV is interested if there's any commercial operations going on by unlicensed drivers. Penalties for such generally are minor, usually just suspension of the commercial activity to suspension of the license and a small fine.
The second would be insurance companies, who now have a list of people who operated in a commercial capacity. Knowing how they like to weasel out of any insurance payout, they can simply use this to note you did commercial activities on a personal insurance policy and use that as justification to cancel your policy. Of course, they won't do this until you get into an accident, at which point you do get a payout
Third group would be tax agencies who are very interested to know about your income-generating activities and did you report it on your income tax form. This takes a bit of work since they generally don't have access to the driver license database to look up people. Maybe you find out when you try to renew that someone wants to have a nice talk first.
Fourth, well, taxi companies who exert a little pressure on someone to take the driver license number and put them to names and addresses... and I'll leave that one at that.
The link between person and drivers license isn't only held by the DMV or similar agencies - if you've ever used a driver's license as an ID card, well...