AIBU to believe that this is a crime? The police say no

[powertoyourelbow]

Name change for this as outing. Person A drives into person B’s driveway. Person B drives into drive some time later. Person B sees person A and tries to reverse out to leave as they are frightened of person A. Person A jumps out of their car and opens person B’s driver door. Turns off their engine and takes keys and returns to their own car. Person B is too scared to runaway . Person B Calls 999. Police treat this as an emergency and come as blue light. They negotiate with person A and get car keys back and give them to person b person B leaves . No charges brought against person A. Police say this is not a crime.

AIBU to believe that this must be a crime?

If I was person A and I was so afraid of person B why would I be on their drive?

Apologies. I can't alter /edit my previous statement ⬆️ but totally confused myself whose drive it was!!
Ignore my other comment.

The police (actually CPS) not prosecuting doesn't mean person A hasn't behaved in a criminal fashion.

It means the police realise they do not have enough useful evidence against A to get CPS to take it further.

If there were no crime whatsoever, no wrong doing, everything fine, they would not have showed up with the speed that they did, nor would they have arrested A.

B needs to report any/all further action on the part of A that leaves them feeling threatened and they need to do what they can to ensure there is evidence (sound activated voice recorder on phone, phone kept in top pocket, cameras in car and on front of house etc).

If person A was arrested and released on bail, clearly the police believe there was the possibility that they had committed a crime but will need to investigate further. If person A wanted to get something, what was it? Property? Information in the whereabouts of person B's relative? Either way, this wasn't how to go about it and the police take a dim view of people using their physical size to intimidate others. Unlikely this will happen again but people can be stupid if they've been dumped by a partner, but if it does, please person A, keep your car locked and call police. I would have done the same in those circumstances.

Tell them to get legal advice as they could hopefully a restraining order against A.

I agree that a restraining order would e a good idea here.