Some of that was very easily done before, Alexs. I won't say where I put an addition on a house without a permit and it ended up being just fine. The City did not (seem to) care and they've seen it. That was then and this is now. Things have changed unfortunately.
Now days, though, the City is very hungry for money and even has been going back on closed projects and billing for inspections that they previously overlooked and did not do. I've heard they have people just drive around looking for work. When I built my garage I witnessed serveral random people stop by and examine my permit for no apparent reason.
As a professional engineer, it would be a big slap in the face for me to get caught working without one...especially when its clearly obvious that work is going on. I don't agree with the policies, charges, half-ass inspections, etc. but I have to follow the rules. At the end of the day, they have the authority to stop work or make you remove the work and that's just a risk that I wouldn't be willing to take.
People will do what they will though... my two cents.