The electric carts are used as transport to go around the open ZOO that is situated on top of an mountain. As it goes with mountains, they can be steep as so the road that is used for the tour in the ZOO. Of course it has been tested, regulated and approved that this carts are capable of riding this steep route with a full load of people (it are big carts). See Bangkok Post Thailand.
So Travel Tip of the year : Always be ware that safety is not always been checked in Thailand!