The Netherlands are (is?) also very flat. If you go up a tower with a viewing area in one of the bigger cities, you'll see what I mean. You can see really far in the horizon! Maybe it's just easier to bike there so more people do it?
It's my wife and I's preferred way of getting around for date night.
You pay $6/hr to ride one, which, assuming a very generous average speed of 14.5mph (the maximum of the bike), is an end user cost of $0.41 per mile minimum.
It costs me ~$0.35 per mile to drive a car. I also don't have to bother with any apps or worry about the battery being charged, both of which are inconveniences.
Also, just to set the record straight, I own an e-bike as well, and my cost to ride (assuming a 500*30 mile battery endurance) is 4 cents per mile, about 1/10x of what I'd pay for a limebike.
There is an upfront cost, yes, but you're also getting a much better quality bike than what you would get with a lime bike (which seems to be an almost-bottom-of-the-barrell chinese made ebike)
You're paying much, much more than $0.35/mile my friend.