I think the signage is extraordinarily clear and easy to understand. The gray machine is solely for passengers taking the UPX to/from pearson. The green machine is for passengers travelling between Union, Bloor, Weston, and any other GO rail stations; as it is a GO machine, it deducts GO fares, including things like monthly capping, their post-secondary student discount, and allowing for transfers between other GO rail lines or buses and the UPX. The UPX presto reader is not integrated with GO so you don't get a transfer or monthly capping etc.Then why are the green machines doing on a UPX platform? ARRGHHH!
I have long said it would make much more sense to only have the green GO reader and get rid of the gray one, but with this signage they've installed I don't see how this could be even slightly confusing. Suboptimal/inefficient, yes, but not in any way unclear to passengers.