[ntucker]

I think anyone who's used a lawnmower knows the concept but not necessarily the name.

[gowld]

And most people aren't electric lawnmower users anyway.

[zrobotics]

All powered lawnmowers have these switches. Push types have the spring loaded lever on the handle that shuts the engine off when released, and riding mowers shut down when there isn't weight on the seat. This isn't exclusive to electric mowers at all.