Troll much?
I will tell you exactly why. I recently installed the A118 Full HD 1080P Dash Cam. The reason, asinine drivers. See my signature, that's my families entire life behind our truck. The dash cam is peace of mind for all those turds who cut me off, run a red light, stop sign, etc. I'm pulling a trailer and have a shorter stopping distance and A*Holes will still pull in front of me when coming to a stop just so they can be closer to the red light.
Why won't a GoPro work? Well I have a Hero 3+ Black Edition, it won't work. Terrible freaking battery life, won't automatically start recording on vehicle start up, no impact sensor, no saving locked files, no way to continuously record.
The dash cam I have runs on 12V, it starts recording when the ignition turns on, it holds a 32gb card and records in 3 minute clips it saves to the card. It can auto-write over the card continuously forever without me touching it.
It has one button that lets me push it and lock the previous 6 minutes so they aren't over-written. Has an G sensor that detects impact and automatically locks the past 6 minutes.
Unlike the GoPro it has night vision and works in the dark. Has a wider view angle than the GoPro, also has GPS which it writes to the files, should you need that information too.
It's called peace of mind in a world of asinine drivers, crooked cops, and sleezy lawyers.
And why would someone need a radar detector? Because crooked cops and municipalities that are equally crooked. Just read about this one FL city:
This Florida Speed Trap Could Be The Worst In The Country
A city that goes out of it's way to purposefully create speeding tickets.
I think the reasons are justified.
PS: THANK YOU to the OP, this is great, I have not hard wired mine up yet, but I will be doing so now! Great article.