The fact that they don't fly with people (passengers) does not mean that they don't deal with people.
Sometimes they deal with people who are sleep-deprived and fatigued, and under a myriad of other stressors. Scheduling, security, Flight Ops, dispatchers, bus drivers, ramp agents, loaders, handlers, Dangerous Good Specialists, mechanics, fuelers, tug drivers, duty officers, ramp contol, ATC, cab drivers, bellmen, and hotel front desk personnel, all trying to do the best they can on the wrong side of the clock. The resulting cocktail of interpersonal relationships is seldom a walk in the park that would be suited for a person who admittedly doesn't deal well with people.
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