The problem is twofold.
1). For club trials FIM is unworkable. Getting two sets of observers one to watch and one to time would not be impossible at all trials but for the majority would not be feasible. The timing equipment would have to be bought by clubs as well.
2). The FIM are still changing the rules. Any club or rider want to buy the new equipment to indicate a "rollback" or stop if that is taken up?? All you could do is as now rely on observers.
All Motor Sports run different rules for different classes Motorcycle sport does have greater consistancy on the rules. However in Car racing Formula 1 runs grooved tyres and refueling. Formula 3 does not. It's a Junior formula and if a driver proceeds to F1 then He/She has to adapt. The principles are the same. We have much more accessible "grass roots" sport where anybody can compete in most events againest the best, excepting the big National and International events.