It was explained that it's because they couldn't actually close off streets to shoot scenes. Apparently people were still walking through sets while they were filming, whereas in other countries like the U.S., you can block off the entire area and anyone who's not involved in the production have to make massive detours. Looks nothing like Hong Kong? Bay can't even get the geography of his own country right! In Revenge of the Fallen, the Smithsonian is shown to be in the middle of an Arizonian desert... in Washington D.C.! Also, Sam is living in D.C. in DotM and you can see skyscrapers in the background, despite the fact that Washington D.C. has none.
Btw, you might like this if you haven't already seen it:
AoE Honest Trailer
^lol.