good question. I don't know? There are three things I carry with me literally everywhere: phone, keys, and wallet. Any one of them missing in the morning means I have to hunt around the house to find them before I can leave for work. This would not change if I could unlock my car with my phone (I still need to be able to lock my front door and/or let myself in when I come home again, requiring keys)

Modern cars already make it much more difficult to lock your keys in the car than in ye olden days.

And the "did I remember to lock my car" remote-check functionality doesn't seem nearly worth the "now a hacker can remote-unlock my car" tradeoff. It's not like that "did I lock it" check helps prevent a "someone smashed the window and grabbed something out of it" scenario anyway.

I do own a car. Keys in home are always in exact same spot. Phone can we literally anywhere, good I have smartwatch and I can trigger "locate my phone" that way.

I just don't get the idea of unlocking car though app via internet. Neither I get the "keyless entry" (meaning I do not even need to touch the key fob to unlock car) and "start button" (well if you place key in ignition switch then you will not lose it!)

The security drawback is not worth, fixing non-existing problem in the first place.

Misplacing the phone actually. Car keys are either in someone's pocket/bag (then you talk to whoever used the car last) or in a set place in my home. The phone might be wherever I used it last.

Are there cars that let you drive them without the key?

My car allows me to unlock it with a phone from the other side of the planet. But to actually drive, it requires the key to be inside.