Because I've been a part of independent recording sessions with bands who released albums using their own meager funds. It doesn't have to take much money to record and produce a decent-sounding album anymore.
Sure, the two can be comparable if you're recording a solo accapella
'not much' for a 'decent' sounding album
I don't think anyone is debating that music can be recorded cheaply, the point is about standup being easier to produce (from a technical perspective), and unless you're thinking of a solo acapella singer, music requires a lot more production value, even just to get something sounding "decent".