Trump claims the election was stolen on little to no evidence, after losing 60+ court cases across the country trying to find evidence. The sentiment expressed is not analogous at all.
There’s also a difference between how you run and adjudicate a ~100 person NRLB election and a ~150 million person country wide national election. It’s both easier to cheat in small elections, and easier to just call a redo. In the latter case calling a redo is literally impossible (and illegal), in the former it’s a pretty reasonable response.
And yes, Trump didn’t prove anything. He’s just a sore loser.