Rollcage, be careful. If you ever looked into a car with a rollcage, you'll find that the interior space is greatly compromised, some even taking out the rear seats. There will be an overhead beam, and side beams, which compromises entry and exit from the vehicle. Now this would create several problems:
1) Head injury
Bear in mind that if you drive in a car with a rollcage without a helmet, and you impact into something, the beams crisscrossing within your vehicle will possess a risk to your moving body parts. Even if wrapped in foam, your head crashing into those beams at 65 kmph is enough to rip the entire skull apart.
2) Iron wrapping
Rollcages are not indestructible. If it is legal, expect to see a lot of cap ayam rollcages around, and these serve no purpose other than making the car look fast. These kinda rollcages might bend and wrap in the even of an accident, and these steel bars might stab into the passenger or make the recovery of an accident victim from such vehicles extra hard.
3) Difficulty of rescue
In the event of a collision, imagine the driver suffering neck fracture, and has to be carried out of the vehicle carefully. Now if you have rollcages, you'll have side beams and these will complicate the rescue effort. it will take longer time for these people to get the driver out. Now imagine a more serious condition - the car is on fire, and they have to get the driver out. This will turn into mission impossible when rollcages is in the way.