I could be wrong but, despite the title describing ANY subway, the patent itself describes the more complex subway system that STTNG used.

I agree it does seem notable that where most 90s games had subways most Sterns don't. It has to be mandated to some extent. There's a reason why we all call Stern out on their use of 'bash toys' because in B/W days there were toys but most of them gobbled the ball and spat it out somewhere else. Each toy was unique and had a lot of mechanical design to it. Stern's toys tend to be a very similar implementation of targets and magnets. They sure are fast and unpredictable though, which is a good thing!

Stern's no-subway bash toy recipe does tend to be operator friendly. But it also happens to be cheaper. Nice side benefit I guess