The metaphor makes sense in comparing a human walking (SWE w/o AI) to a human riding on a horse (SWE w/ AI), except for:

> (The horse) is way slower and less reliable than a train but can go more places

What does the 'train' represent here?

A guess: perhaps off-the-shelf software? - rigid, but much faster if it goes where (/ does what) you want it to.