Indeed.
Having 4 cameras in my car not with GPS,and with time / clock not synced up i have to resort to recording # in a given driving session.
This sort of work okay as to finding what i need and stitch it together in post production, but i have had to leave out the time/date stamp in those cameras as the not synced time would annoy me.
I am looking forward to getting 2 of the cameras in sync at least, the GPS make things so much more easy.
And i am okay with GPS in a dashcam, on the other hand in my phone i dont use it often and i sure as hell dont have it on all the time as some / many people have.
And H2O dont fear the GPS, if you are worried about some one using the footage against you, well then you should not video your drives as your speed can always be determined from the video footage itself.
Distance traveled in ? time, go measure the distance between 2 fixed things in your footage, time how fast you cover that distance, add a little math, and you have your exact speed.