These execs were arrested for running an illegal company. Drivers may be arrested for driving an unlicensed taxi. I do suspect the former is the more serious charge, especially as the business of Uber has been declared illegal already in France, and the bosses decided to continue anyway: that's contempt of court, and courts tend to not be happy with that.
If you want to stop a business, you have to chop off its head, i.e. go after the bosses. The bosses of Uber don't care for drivers to get arrested, that's just collateral damage to them. They still make lots of money off the other drivers. Getting arrested themselves may finally get the message home that they have to follow the rules and regulations of the country they operate in, whether they like those rules and regulations or not.