Someone can die and be just as dead regardless of the level of automation the aircraft possesses. While I agree with your sentiment, 135 time is better experience in many cases than 121 time SIC, one should be paid for the level of responsibility they are assuming, not for what they actually DO.

A ditch digger works harder than I do every single day, but I make a hell of a lot more. The difference is that if the ditch is dug incorrectly, you just fix it. You can't undo a mistake in the aviation world.

Same thing with lawyers, doctors, CPAs, and other professionals, they never get their hands dirty, wear starched shirts, and sit in A/C all day. But if a mistake is made, lawsuits fly - and that risk deserves adequate compensation.

An FO for 121 is second in command. As such, he/she should not get PIC pay, of course. But should the captain have a problem, who is responsible for the safety of the multi million dollar airplane and its occupants? Decisions will be made that could bring largely different outcomes in the end.