When I was a fresh faced youngster in the right seat with two shiny bars, the old bold codgers in the left seat, with dulled out four bars gave me this advice -
"when it looks like there is just enough space to pass - there is not enough space to pass. When it looks like there is plenty of space, that's when there is just enough space to ,"
"laddy, you only get one chance at a taxi accident"
So whilst I generally agree with Sam, Tango and Top Bunk, I think it is being over simplistic to simply state " Its basic airmanship" or "totally indefensible"
In the airlines I have been in this has happened 5 times ( over 23 yrs) and I was able to chat with all 5 and each and everyone "thought" they had enough space. They were not trying to sneak past. By the grace of Him upstairs this has not happened to me, but how many times have we gone into, say a new airport, and occasionally had the exhaust orifice pucker up a notch as you thought - gosh this is a bit tight, as you taxi exactly on the taxi line and all other aircraft appear to be behind the lines ( it there is a line).