Depends what the alternatives are as to whether they are exploiting artists.
broadly speaking, artists get about £1 for each cd sale or .2p for a stream. Based on that it looks like a bad deal.
But streaming isn’t just a substitute for purchasing. Like you say, you listen in the car, where it might have been radio 2 or some godforsaken transatlantic network bollocks 20 years ago. Radio 1 or 2 pay £100 to £150 per play. At, say 1m listeners that’s, erm .... a fair bit less than 1/5p per listen. I’d rather have £2k per million listens than £100.