I get offers for my domains, all unwanted.

If I at some point decide to sell one of those to one of them, all the cold approaches from the past don't suddenly get legitimized.

edit: as I'm writing this, I remember that this is quite similar to the selling of social media IDs. Some random crypto start up decided that they should try to bully me to sell them my three letter Twitter handle. Really annoying.

My state department of motor vehicles maintains a database of vehicles registered in the state and the contact information for their owners. While they do not have a convenient website for querying this data themselves, they make it available to third parties in bulk, and I can obtain individual records for those third parties convieniently using their websites.

Both these databases are mandated by my state legislature. So it seems the same reasoning does apply.

Another difference is that this contact information does not, AFAIK, include recipient-paid [1] contact methods such as mobile phone (including text) and e-mail. Also, methods such as phone are generally considered far more intrusive that, for example, paper mail.

[1] nowadays this is mosty nominal, but we're not quite at zero