Originally Posted by
ECL_FTE
In North America, the factory layout is sliding door on both sides (that's the standard on the production line in Columbus MS). For aircraft coming out of the French production line in Marignane, the standard is left hand side sliding door only. The right hand side is extended cabin door.
You're mixing
standard with what the preferable option the customers are ordering.
Standard doors (what you call ''extended'') is specified in the limitations section in the FLM, which also lists the different options you can order. It might be that the customers in the US prefer the sliding doors option on both sides, but it is still an option. They are incompatible with the squirrel cheeks, so plenty of machines without sliding doors in Canada.
In Europe, Africa and Asia, the most common model I've come across is the option with sliding door on the left, with the odd dual side ones and the really odd ones where you only have it on the right hand side. Flown plenty of standard doors where the majority had cheeks though (which are really great, after they came out with the forward hinged mod for the doors) For utility configuration, sliding door on the right is the least favourable option.