It was supposed to be for covid I think, but worked after for a while too. The commuter card just verifies that the charge is billed as something under "transportation" (and probably that it's not airfare). It's the Lyft/Uber app that appears to stop you from using the commuter card for non-shared rides.

Honestly (and since this is a hacking forum) I have a theory that if you could hook the Lyft/Uber app with Frida or a modified kernel you could push through payment using a commuter card on regular Lyft/Uber rides.