From my own experience in the sim I have deduced the following:
A takeoff will only be recorded in the log book if appropriate clearance has been given for the take off from ATC. (If no ATC clearance for take off is given then it is unlikely the log book will record a takeoff!) For touch and go’s takeoffs can be recorded, iirc, if the aircraft has been cleared for a circuit by ATC and slows below a certain really slow speed on the runway, before taking off again.
Landings only seem to be recorded if, again, the airspeed drops below a certain low limit… No ATC clearance seems to be required to “log” a landing.
Is this the way the developers intend it to work? I have no idea. The concept of wheels on the runway and wheels off the runway would make sense to me in terms of recording a landing or takeoff.