Emmission standards are not monitored

Do people know that emissions standards especially for motor vehicles are not monitored after the car drives out of the showroom and off the forecourt? Do people know that no matter what the advertising of one petrol brand over another there is no guarantee of "clean and dry" fuel out of the bowser? Do people know that... we change oil at the same time as changing oil filters because the filters have in effect not worked, i.e they have failed to keep the oil clean. Imagine a swimming pool and its filter, it'd be a bit rum if every time you cleaned the filter you had to empty the pool and refill it with clean water. That's what you (or your servicer) in effect does every time your car goes in for service! There is so much we can do in a highly practical way to improve our emissions but the OEM's together with general societal ignorance conspire and collude to perpetuate 1930's technology.