The quote from the answer suggests a slightly different motivation than reducing screen time.

> I use a setup similar to the above to allow an automated train to run around my son's city without the need to have a screen nearby the whole time.

It’s a criticism that I hear regularly of the requirement to use an app for various of the motorized Lego kits: Having a phone in hand often leads to the result that the kids stop controlling (or even building) the kit and rather start playing on the phone. It’s also a bit an expensive thing to hand to your six year old so they can control their Lego train.