Did you try moving the steering wheel when you are having this key problem?

There is a lockout in the steering wheel so that steering wheel locks in place when the key is out of the ignition (this is pretty much standard). Sometimes on some cars, you cannot turn the key if there is tension on the steering wheel...

Do you use the steering when to pull yourself out of the car, thus "Locking" the steering by applying torque to the wheel?

Additionally, when you park the car is it on FLAT ground or is there an angle or incline in the typical parking space? Reason I ask, is that if there is an angle, then the terrain will keep pressure or torque on the front tires and thus keep the locking mechanism under strain so that the key lock appears hard to turn.

Any or all of these things can be the culprit...

Give that a try...