There is a heavy emphasis in "Thomas" on being useful. That's not an unreasonable thing for a train to want to be, I suppose. Heck, there are worse things for a person to want to be. But it's been subtly bothering me for the past few days (as we have watched "Thomas and the Magic Railroad over and over and...). I think I finally figured out why.
In Econ 101, you do your work in units called "utils" that measure utility. It's made clear that there is no one right, unfixed standard of utility, and that the thing which you scarcely value now may be very valuable later. (Standard undergrad example: the first slice of pizza, when you are starving, is worth more utils than the sixth slice of pizza.)
If you aspire to be useful... according to whose standards?