Speedy Justice?

Just watched a piece on citizen speed radar traps. With kids I totally agree with any form of traffic calming. But sorry, not by anyone but those trained and legally tasked with doing so. Not some granny with a gun.

Are these devices reliable?
Are the operators' eyes reliable?
Are they sure to be objective?
Are the records held against other traffic infractions?
What is the opportunity to appeal and have the records expunged?

Can I get a local neighbour to assess me for tax?