This has happened recently in NSW in Australia.
A guy had a new clutch installed into his Porsche Targa. Mechanic took it out for a test drive. The car is bright yellow,and it obviously caught the police eye and was pulled over.
He received a Defect notice and a directive to remove the after market roll cage section from around the driver/ passenger area.
The car had been driven and road registered for 10 years in this condition!
It has also been in the Targa Tasmania at least 5 times.
The owner has an unblemished 40 yr driving record.
The RTA's position is that the roll cage could intrude into another vehicle in a collision!

The 1976 Porsche only weighs 1030 kg, most 4x4 between 2000 and 3000kg.
Imagine one hitting my car at 60 km/h ?
I wonder which configuration the RTA would like to be sitting in at their crash test facility, with the pen and note book ready?
My car does not have a roll bar and I wonder if a Morgan owner over here could be forced to remove that vital piece of safety equipment using the same silly logic?
what happens here today may happen in Dear old England next year!