I think a huge part of our problem here in Florida is we have moved so fast and so strong on beefing up the building code that nobody really understands what it means, Calling for engineering is just the way the building department is passing the buck. The engineer passes the buck to the state that gives him "typical details" he uses.
One issue I had was an 8x16 concrete beam 14' span. The engineer told me that 4 #5 rebar in this would carry any load he could reasonably compute in a single story house (just the roof load) I had spec'ed 2 #7s in the bottom and 2 #5s in the top. The handout from the state said 4 #7s and 2 # 5s so that is what we did. http://esteroriverheights.com/electrical/addition/14tie_beam_steel.jpg
I was just not sure why the building department couldn't just tell me that. This beam is smaller than the one over a 2 car garage door and I bet they permitted 1000 of them since the 2006 addendum to the code.
I even needed engineering for the slab footer and that is probably 75-80% of the houses they build here. The Mexicans who worked for my mason knew how to form and steel the slab.
When I talked to the plans examiner she said all structural concrete needs engineering, no exceptions.
BTW my electrical plans sailed through. I took some comfort from that