Mark hazard where report was started, not submitted
Also, allow people to not only thumbs up a hazard but also adjust its position.
Perhaps that could be an option, but it shouldn't be the only way of doing it. It's one thing for me to tap a couple big buttons on the screen while driving (I have my phone on a dash mount, so I can do it while still keeping an eye on the road, and it's less of a distraction than messing with the radio). But to look at a map and try and figure out the exact spot something is would be too distracting. It doesn't have to be perfect, but placing it like I suggested would make it a lot more accurate than it already is. A better way to do it based on your suggestion would be to allow other drivers to correct the position, so somebody driving could report it and have it be close enough, but somebody riding as a passenger could come by and move it to a more accurate location.
That is the totally ass backwards solution to a broken reporting system.
I agree with you 100% but instead, why not just let people specify the exact position where the thing is! Then you wouldn't have to try and figure out which position is correct, based on which user managed to get his phone out in time (or turned his car around to get an exact position report) or another user wouldn't have to go back and fix something that the OP could have just been more precise with to begin with
If everyone could just touch the map where the report should go, none of this would be an issue!