A few additional comments as an occasional user of the ABE bus flights:

In general, they are a really good thing. I think the odds these days are in favor of the bus driver and I-78 delays versus a pilot and EWR/airspace delays.

On one trip a few years ago, the bus driver offered the passengers an "in-flight" snack: candy canes (IIRC) before the bus departed.

The departures from EWR to ABE are fun, with the bus passing almost beneath the wings of planes parked at the C concourse.

The OP's comment about rail service is right on, of course. In lieu of that, it's worth mentioning that Trans-Bridge Lines provides very good bus service between various spots in the Lehigh Valley (including their LVIP headquarters very near ABE) and all 3 terminals at EWR. No EQM's either but fares from EWR may be cheaper than from ABE. And they may not. It's nice to have the option, though.