A and C
I am glad to say that you are wrong about the closure of PUBLIC roads in the UK mainland for motor sport events. It doesn't happen! It occasionally happens in N Ireland, but not elsewhere in the UK.
The "roads" used for stage rallies are all privately owned, in many cases by the Forestry Commission and the safety regime involved, aimed at ensuring spectators don't stand in risk areas is very well developed.
Meanwhile, this week many hundreds of miles of PUBLIC roads are being closed for lengthy periods for the passage of the Tour of Britain bike race causing not inconsiderable inconvenience to many!
This tragedy will have negative effects on the whole airshow business, both those who create and those who spectate, not least through insurance limitations. It is already reported that a multi aircraft Spitfire formation is unlikely to overfly London soon for this reason