The streets are filled with companies using public spaces: Fedex deliveries blocking the road, sidewalk signs for bars, Getaround rentals, food carts, mailboxes, ATMs, parking meters, Scoot scooters, taxi lines, Lyft/Ubers, Redbox DVD rentals, annoying Greenpeace petition people, construction, billboards, etc.
I don't think it's a cost-saving measure for scooter/bike companies, but rather convenience for users. I wouldn't use scooters if I had to walk 4 blocks to a "designated pickup zone".
Yes, these scooters/bikes are making money. But they also really improve cities, by cutting down on traffic congestion and car emissions. As long as they're regulated via permits (meaning the government makes a bit of money to pay for maintenance), they should be allowed... and if people dislike them, they'll go out of business, and it'll solve itself.