It's a supply and demand thing. There are so many musicians, the idea that they all can make a living doing it is simply not realistic. Only a very few will, regardless of whether they make a few pennies off of streaming or not. Having the government pay them through taxes is a terrible idea.
I know many people who are musicians. It's always a side gig.
I know artists, too. No money to be made there, either. Maybe a few pennies at the local arts&crafts fair.
The Law of Supply & Demand again is in play. More musicians => less pay for each.
The underground is dying though due to a plethora of other forms of entertainment. Shows were a great spot to get some social interaction, but people just don't go out as much anymore and are more likely to do discord and videogames instead of hitting up a basement, bar, cafe, or warehouse.
Which would include the family of working musicians | fencing contractors over the road from me in rural Western Australia.
The husband and wife lead performers are in their early forties and have been playing music live for 20 years .. they sell recordings but their main music income is hotel venues and music festivals - they tour almost half the weekends of the year, mostly local, sometime by plane to the other side of the country.
When not touring they're building fences by contract (ATM mostly around solar setups for Telstra and mobile repeater towers in the rural telecomm domain)
They're not a super band, the live performances pay for themselves and turn a profit, all up they're making something like $200K (AUD) per annum from both jobs.
They're not especially well known by name outside of blues hotel gigging.
Like it or not, that's always going to be the case. The Law of Supply & Demand cannot be repealed. It's in play even when the government fixes prices and payouts.
Artists have almost always been poor unless they found wealthy or state sponsors.
The subject is broader than musicians only.