We were recently discussing this issue of insurance (purchased with the rental) when another member had an issue with returning a rental.
You need to know exactly *what* the insurance covers. For example, if it only covers damage, then you might decide to simply walk around the unit and snap photos of it from 4 or 5 angles with the camera in your phone, and go on.
If it covers lost/stolen units, that's a whole different critter.
If it offers any additional medical coverage (say you accidentally run over another Guests foot - not assigning blame, because everyone here has had someone walk *right* in front of them, so it *can* happen), that's a whole different critter as well.
If the unit is lost or stolen while it is in your possession (before the rental company has picked it back up, and put it on their truck) you could be on the hook for the entire replacement cost of the unit, at retail. (This could be anywhere from $350 - $2500 depending on the
scooter) If you cause injury or harm (to yourself or another) you, or your homeowner's/personal medical insurance could also be on the hook for all costs.
So, you need to know not just what the insurance covers, but what the contract says as well. If the contract says you don't have to worry about "normal wear and tear", then document the condition of the unit at delivery (ideally with the driver present, and in one of the photos) and go on down the road. If, on the other hand, it says you are responsible for everything that happens to that unit, and with that unit, then you might want to consider their rental insurance coverage.
Having said all that... you also can reach out to your insurance agent, and ask what (if any) coverage your homeowner's policy would have in a situation regarding the rental. Your deductible may be so high that you prefer to buy the rental company policy, or it may be that your homeowner's coverage would be more than sufficient.
So... TLDR; You need to do some homework. Everyone's situation is a bit different, and everyone's tolerance for risk is a bit different. I would start by requesting a copy of both the rental contract, and the insurance, and read them. Any company that won't allow you to read a contract first is not a company you want to do business with anyway.