Depends on where and how far you are going. If you dont absolutely have to have folding bikes then do not get them. If all you need is transportation a short distance then, yes, get the cheapest piece of junk bike walmark sells. Bikes get stolen. Homeboy is tired of walking so steals your bike. Cheap bikes are not such a tragic loss, and cheap to replace.
Hills need to be considered. Nothing stops a non-cyclist from riding like hills. Ideal to have a flat area you will travel on.
a quick store visit you can lock the bike up, but longer stays the bike might be gone when you come out. With two people one can stay with the bikes if needed.
I use a small bike lock for very quick store visits, and where I can see out the front window at a glance. I dont trust anyone, and my bike is way way more better than walmark garbage...
Scooters are better, faster, wider range and easier to use. They are harder to steal being heavy and needing a key. If you have room for a scooter that is great, but I would not go out and buy one just for your first rental trip. Use what you have. Borrow some cheap walmark bikes for your first trip as the bikes might never come off the rack either unless homeboy steals them off the rack too.
I never need to do a store run as I just buy what I need before parking. The one store run I did was to get a part to fix the truck, and the truck was down, so bike only option. I use bike for recreation, not errands.
Also a BIG factor, and I am way way more fit than anyone who has even seen this forum, is that riding a bike will make you sweat and get a little dirty if you go any distance (10 mins or more) and especially if there are hills to climb. And if you wear a helmet then your pretty hair is messed up for the party. With an electric assist bike or a scooter you will not sweat. This is something to consider even for the fittest rider. As good as it is to ride a bike and not use gas or spend money on gas or batteries, the reality is that your choice is "do I want to get sweaty right now or do I want to just drive?", and often the answer is "dont want to get sweaty".
The Europeans get sweaty, but Americans like to stay clean, so the bikes tend to stay on the rack in reality.