There's a very good reason for that
Spotify has a free tier which pays less per stream but also has a massive security issue right now. They pay out once 30 seconds of any given track is played. This facilitates stream farming, since that permits a maximum of 2880 streams per day. The money one can make from exploiting this estimated to be around £6/day which adds up pretty fast if you multiply the number of machines (virtual or physical) that you use to do this (£2000 per-machine, per-year). The audio can be piped to a virtual audio device to dodge having to listen to things and your hacked client can run in the background, fully automated.
In fact, this is so easy for people to do that if you, the reader, just wanted to stream enough to get Spotify for free each month, you and some of your friends could just upload a few performances of your own and each play them in your sleep for a few hours using a playlist. With ASMR being a legitimate option, you can just pick some interesting foley sounds and talk in a calm voice to make content which is beyond merely plausible deniability. No hacks, no machine farms, none of that is required. Just play a mix of your and your friends stuff for a couple of hours while you sleep with wired headphones attached using a playlist. Doesn't even have to be every night.
This is where the the problem for Spotify comes in when it comes to how much they can afford to pay artists. The more streams which occur, the lower the payout will be per-stream because there's a limited pot of money based upon a percentage of the combined subscriptions of all Spotify users. A potential solution to this could come in the form of rate-limiting payouts, such that any artist can only be paid a maximum per day/month/year for any given individual track per individual user account to prevent abuse. However, at throttling levels which artists are likely to accept, one would only cause farms to scale up. One would have to make it unprofitable to abuse the system at all by applying very thorough throttles, with the idea that artists would get a greater amount per-stream in exchange... the maths is not on Spotify's side there.
At the moment, it would be corporate suicide for services to attempt to standardise rates because at a fixed rate per stream, the service could no longer offer unlimited listening for consumers and once again it would become more convenient to fire up a P2P client and download everything without paying a penny. Plus, services like YouTube put music on the same pedestal as all other video-based content, at which point, standardisation becomes nigh on impossible.
I wrote way more than I intended to here but I hope someone on the Internet finds my take useful :)
Biting the hand that feeds IT
