A house is a private place - you own (or rent) the land and the dwelling, and with that comes the right and expectation of privacy. A car is a way of moving th

A house is a private place - you own (or rent) the land and the dwelling, and with that comes the right and expectation of privacy. A car is a way of moving through public space. There's no automatic expectation or legal right of privacy there, any more so than in public buildings, parks, on transit etc where people are walking around.