Car makers cannot do anything they want and call it a car. The motivation there is safety, but it's long been argued that personal computing devices are today extension of our lives.

Even more comparable is postal rules: at least here, there are very explicit rules about opening someone else's mail, or even destroying it. Even if postal/courier services are businesses, they have to operate within the boundaries a society sets up for them.

And finally, you can take it even further: some "businesses" operate on the fringes of legality and sometimes illegally too (think loan shark operations, casinos, betting markets... but also "protection services" and similar).