Also the park flyers in general are made to be light, not strong. The flimsy foam that most are made of turns to confetti if it strikes something and as such is the opposite of a sturdy easy to repair trainer that is made of balsa and plywood.
This is not allways correct.
There light weight and slow speed allow them to survive crashes with minimal or no damage that would destroy a glow powered trainer. Repairs are easy and quick requiring only epoxy and or white glue and toothpicks.