Pop singers post vast amounts of stuff on YouTube, SoundCloud, Spotify etc and also on Facebook with links.
This in itself gives them exposure, but probably no money to speak of. Pop artists usually make most of their money from live gigs, but that's no walk in the park since when you are starting off it's usually pay-on-the-door or even pay to play.
So they have plenty of opportunity to "record" and do so in great numbers, but that's not the same as a commercial release. Classical singers do some of the above, but much less. They also record a lot of lessons which they post on YT and elsewhere, and make money teaching online. This mushroomed in the pandemic when there were no live gigs.