I’m sure many of us will be expert on failing the “field impairment test” without the need for alcohol or drugs.
To enforce any of these checks, first there will be a need for some police, something we don’t see anymore. What we do see is drug deals taking place openly out of car windows, people reversing cars into our cars in residential parking whilst they are clearly stoned or drunk (probably both) & then driving off, and drug dealers pointing guns at you at junctions as they feel that your indicating to turn right is infringing their rights & is in some way a racist act.