I think you're mostly right, and your example (sales work with big companies) is well aligned with your theory, but there are plenty of schlepps that are not conceivably anyone's passion because they don't require any differentiated work. My personal favorite example is a service that will perform DMV operations on your behalf (where the primary work involved is standing in line). Whenever I need that service, I am ecstatic to pay the $50 or so that they demand rather than lose rand()*4 hours of my day.

Similarly, while someone somewhere is probably excited to work on Stripe's fraud and security problems, I suspect there's a ton of paperwork that must be filed and waited-upon in order to operate such a service legally. I know plenty of lawyers and none of them consider that sort of thing fulfilling work.