The rear camera comes on immediately when you shift into reverse, but the front parking assist camera requires one button push (IIRC).

 

Correction: my front camera comes on when I am pulling into a parking space (no extra button pushing) - I don't know if (or how) I configured it in the past or not.

 

My 2023 Limited (USA) front camera with the assist lines does NOT come on when I slow down...I have to push the parking button which is on the next to the end on the far right, above the center row of buttons. I to press that before the display comes on...is there some persistent setting? I can't find it anywhere.

 

I think that the front camera comes on when slow and the proximity sensors see that something is close.

 

That is the way my Tacoma works, but my Ionic 5 is requiring the button push, which is annoying, since you are pulling into a space, and have to pause and reach to push the button. Surely there is a setting to change this behavior.