You ARE allowed to exceed 250 knots under 10000 if have permission granded by ATC. ::)
"if you have permission" being the key phrase. ;)
thats not saying much considering that most of the regulations in FAR part 91 start with the phrase "unless otherwise authorized by air traffic control..." i mean honestly... a pilot could pretty much do anything he wanted if he had a controller willing to grant permission.
as someone who works in the airline industry i have the privilege of frequently viewing southwest airlines getting star treatment out there
times when ATC says "oh your going to miss that crossing restriction because your too fast?... thats ok." the proceeds to move everyone out of his way to accommodate him. why should I take a 70 degree heading change AWAY from my destination while southwest gets to go direct when HE f'ed up?

or how about this frequent exchange?...
ATC: "American 123 say speed."
AMR123: "American 123 is doing 250 knots"
ATC: "American 123 roger maintain 7,000 i have a southwest jet at your six o'clock same direction at 5,000 with a 30 knot overtake on you."
how can the southwest jet
legally have a 30 knot overtake? ::)
well there is always the argument that radar see's
ground speed, and the 250 knot requirement deals with
indicated airpseed but when both aircraft are on the west bound arrivals and the winds at 3, 6 and 9 thousand feet are all out of the west at 10 - 20 knots??? if anything these guys should be going slower?
it happens
all the time.
im not saying southwest is a shatbox operation... because they are not, but they do a good number of things that are not necessarily in the book or just flat out go against the book if you know what i mean
everyone looks at that cheap, cattle car, redneck catering southwest airlines as if they are the best in the world because you can get on board with a blood alcohol level that should be rendering you comatose... my argument is that its about time they got shafted.. even if its just a little bit. :-/