Matt - no doubt it is a good concept but there is hardly a system that a "good" operator can't find a way to defeat it if they don't want to be bothered with it - drives Engineers crazy for sure. The simpler the design the easier it is to defeat. As an example, on sit down rider lift trucks there is a safety seat switch in the bottom cushion to prevent the unit from function without an operator present. A simple GEM or any other brand paper clip can defeat this.

Years ago Ford Motor Company required all their lift trucks to be fitted with an "inch pound" overload device to prevent the trucks from being overloaded. Mind you, that when they bought a truck to be rated 8000 lbs. per their safety standards (much greater than the ASME/ANSI standards) normally a 10,000 base rated chassis was required. They spent about $2000- 2500 per truck for this required optional safety feature. Between the operator's trying and succeeding in defeating the systems and the suspected reliability of this safety option it was dropped as a requirement in the Ford safety standards in a few years.

In my opinion, having the operators wear seat belts is a management issue.

A very simple option available is seat belts with bright orange straps in lieu of the standard black belt. This makes it much easier to visually police who is and who ain't wearing them.