The first thing I do when I get a new laptop is wipe the hdd and install my preferred OS, which entails also installing my favorite browsers. (My OS choice doesn't come with a browser, or much else it's all up to the end user)

As for mobile devices, here too I always install my preferred software, so I don't see how mobile devices have lower configurability. That said, there exists databases with which one may at least identify the mobile device in order to serve up content appropriate for that device.

Alas, my tendencies make my devices uniquely identifiable!

(From Panopticlick) Your browser fingerprint appears to be unique among the 3,140,429 tested so far.

Currently, we estimate that your browser has a fingerprint that conveys at least 21.58 bits of identifying information.

That's for FreeBSD running Xombrero.