I've recently observed with the SMT (remotely). It's a good telescope and you all do a great job running it!
(it seems that gasoline station owners here in Massachusetts got a different memo, though)
Despite the fact that the outcome is similar, there's a legal difference between "surcharge for credit" and "discount for cash". The former is/was illegal, the latter is legal. Presumably gas stations in MA and elsewhere are doing the latter.
"An open mind has but one disadvantage: it collects dirt." -- a saying at RPI