I really do mean abortion doesn't weight 300 pounds for everyone. I, for example, don't care much at all about abortion - it is almost entirely divorced from my identity - so I do not have to use much in the way of 'rationalist muscle' to avoid the gravity of emotional bias. On the other hand there are some topics about which I am passionate. Those subjects may weigh more for me than they would for some of the people for whom abortion represents a huge burden of temptation towards bias.

This was just a tangential thought that your analogy prompted. What constitutes 'politics' is itself subjective and can be fit into a bench press metaphor where the weight is intended to represents fighting bias.