Of the scooter companies that have launched in the Bay area, Spin were by far the least technically advanced - the scooters were basically unmodified Xiaomis, to the extent of still having power buttons. Rather than an integrated location and management system, location data came from a off-the-shelf GPS tracker spliced off the battery lines. Since the scooter control board had no cellular link, there was no mechanism for Spin to directly manage the scooters which meant that handshaking involved the app notifying Spin's API that the user was going to hire a scooter and then sending an unlock code back to the scooter via Bluetooth. Locking was the inverse, which left plenty of opportunity for state to get out of sync (server thinks scooter is unlocked but the unlocking failed, or vice versa).

It's possible that their launch was very much an MVP and they've been doing a lot of engineering work in the background, but they were way behind Lime and Bird at launch time.

(Edited to clarify that the unlock code is sent via Bluetooth)