Manufacturers design ultralights which just barely qualify so they can offer the most performance and features possible. Some owners then add bigger engines, more streamlining and other options which take it over the limit. The government relies on more or less voluntary compliance because they will never have the resources to hunt down every ultralight that is slightly over the limit. They realize that a little extra weight or speed does not significantly increase the risks involved. Exceeding those operating limitations very greatly compromises safety.
Usage is free and can be anonymous if desired.
Ultralight and hang glider pilots have long used emergency parachutes which are attached to the aircraft instead of the pilot. You don't have to bail out. Instead the pilot and the aircraft float down together. Manufacturers have claimed a deployment in only 2 seconds which allows for a possible successful deployment as low as 100 ft. Some designs pack the chute very tightly inside a canister.