Apparently X-wing pilots can fly Ties- the only thing is they have to get used to is the speed, maneuverability and lack of shields.

Technology is fairly standardised in starwars- there was never an instance of someone not knowing how to use stuff- as in the aforementioned Deathstar example- they knew how to read all the monitors and use all the computer consoles and equipment- enough to know how to navigate a station the size of a small moon and take out tractor beams and get into a detention block.

An exception might be Luke blasting the control panel, but he's a farm boy who's never been off world.

The following acts of 'liberation of materials' in the movies:

Ep IV: Stealing stormtrooper armour and successfully infiltrating Deathstar
          using unfamiliar stolen E11 blaster rifles to deadly effect
          hacking the imperial systems via astromech droid
          Turning off tractor beam by means of a switch
          Smuggler operates imperial comm system
          farm boy operates unfamiliar turret gun to shoot down trained imperial tie pilots

Ep V: Smuggler is familiar enough with Imperial fleet equipment/procedures to know where their sensors can't find him and to know when they will dump their rubbish.

Ep VI: Rebels use stolen skiff speeder to flee explosion of Jabba's sail barge.
          Thereafter use skiffs magnetic winch system to retrieve droids from sand.
          Use stolen shuttle and stolen codes to bypass Imperial fleet security (with help from dad)
          Rebels (and an ewok!) successfully use stolen speederbikes to navigate forest at speed.
          Chewbacca ganks ATST while Imperials are still inside (can we do that in game pls?)
          Luke flys Imperial shuttle away from deathstar II .

''Its over. Angel won.''   RSF Gurd

why lock them? you'd only forget that and try to steal one and get killed cause you forgot they're locked

Stardestroyers basically has it right I think.  The ATAT requires a lot of specialized training, but down from that everything is extremely simplistic as the empire focused on producing simplified, lesser technology that could be utilized by larger, sacrificable numbers.  All through lore you see if you can fly an XWing or a TIE, you can basically fly any starfighter used by the rebellion or the empire.  Also, you must note that a large percentage of Rebellion members (somewhere over 75% of human members) were Imperial defectors who had attended some form of Imperial military academy and would be familiar with all Imperial technology.  It's safe to say, with the Rebellion's style of fighting, these defectors would be utilized to train the rest of the Rebellion in how to operate stolen technology.  If you want to think about it in real world terms, if you can drive a car, you can probably handle a truck after a minute or two of practice.  The biggest difficulty you might encounter between vehicles is a shift between an automatic and manual transmission, which is really not that hard to overcome.

Personally, I don't want to be attacking a CP, see a Rebel standing outside of his vehicle repairing it, and be unable to kill him and grab the vehicle.  That's just not fun, plain and simple.