TP are also human beings. They also have their mood swings and
temper. So, it's bad luck that you met one who decided to "abuse"
his position of authority. A word of fairness, not all TPs are like
that. I think most are just sick of dealing with so any people
every single day trying to use all sorts of excuses (sometimes
really blatant lies) to wriggle themselves out of a fine. So, they
have to act stern from the start to do their job.
Remember there was once when my dad got stopped by this young TP
(maybe too greenhorn). He was very polite and kept addressing my
dad as "sir" even though my dad was so worked up about being
stopped. In the end, I had jump in to placate my dad. Well, he got
a fine and demerit points. But at least, the TP merely did his job
and showed us the respect that all citizens in a democratic society
are due. 
