Since the code came in accidents have reduced by over 90% and even the dark side of the magical community has seen the advantages of that. They've stopped losing their best people for stupid reasons. They can focus on losing them instead in the standard all out battles with the good side of the magical community instead. Funnily enough everyone is happy with that. It is what is meant to be. The code then is a great unifier.
Broomsticks vary in range of flight and weight capacity so are grouped like our cars are in terms of what restrictions apply. The slower brooms have lower limits to stick to and all fliers are expected to know what their machine can do and what speed it should obey.
Most do (who hasn't had to get away from a dragon in a hurry after all?) but there are idiots who do not and those are the ones hauled in by Hanastrew and her fairy squad for traffic regulation infringement. The latter are widely suspected by the former of just "filling in their books" but the squad do not haul in folk without reason (and it is usually to clear the skies of idiots who don't know what they're doing so everyone else can get along with their magical business, lawful or not, without fear of being forced out of the sky by an inexperienced flier. The Kingdom has a long history of accidents caused by such people. The only positive thing from the inexperienced fliers' viewpoint is that it is better to be caught and fined by the fairy squad than by the witches. Now there is a group who really do not "do" forgiveness!).
Each magical group is tested for its flying capacity by senior members of their own group on the grounds there's no way a wizard would ever accept any witch commenting on his flying or vice versa. All magical examiners have to follow the same standards and are themselves tested on their abilities by the entire Queen's Council (which is made up of one member of each of the 22 different species in the Fairy Kingdom).
Magical beings are expected to take notice of all road signs and commands. Failure to do so will, at best, lead to massive fines and possible imprisonment. It is much more likely to lead to instant incineration, especially when ignoring the Beware Dragons! Symbols dotted around the realm. It is literally a case of on your own head be it.
As for tailgating other citizens, whether flying or on the ground, are you mad? Given the Kingdom has a wide variety of magical beings with differing powers, most of whom do not practice forgiveness on a regular basis, you really would have to have a death wish (and a particularly horrible one at that) to behave like this. Even if it is "only" the law that catches up with you, the fairy squad are known for their robust approach to law breakers. No soft options here. Being hauled over the coals is a real threat here.
Regarding enchanted items such as making cars fly, they have to stick to aerial speed limits as well as those set on the roads (of yellow brick construction or otherwise). All enchanted items have to be declared to the Queen and her Council as they want to know the amount of magic used to create these things and their capacity.
It is recognized that dark wizards and witches will attempt to hide such items, certainly they won't declare capacity voluntarily, but once out and about if hauled in by the fairy squad, they risk imprisonment and the total destruction of their creation if they haven't declared it. A common way around this is to declare the item but accidentally on purpose underestimate the item's power output. It is difficult to prove under-estimation given any wizard or witch worthy of the craft can make their vehicle perform as badly or as well as they like depending on what the occasion requires.