Ah! but tachographs won't say if you have the seat belt fastened or are using your mobile. Frankly, I can't see them going mainstream for mobile cars. In Europe, PSVs and HGVs are mandatorily fitted with them but they are rarely used for speed controls except where a driver contests a radar control. Their main function is to ensure the drivers do not exceed the number of hours they are permitted to drive and they take the necessary number of breaks. Taxis have to be fitted with them in a few places, as well. AFAIK, nowhere is it necessary for private cars to be fitted with them.
It is NOT true that cameras are being generally decommissioned. In fact, they are springing up like mushrooms in most places because they are an excellent means of generating revenue. I know one relatively small area (much smaller than Cyprus) where they have just ordered 150 cameras and 300 housings.