there's a big difference between being able to hear a difference and being able to fix tuning in real time. almost anyone could tell you by listening that the notes aren't the same pitch. most will be able to tell you which is higher, and fewer will be able to identify intonation in context.
That's certainly the case if you play two notes next to each other and then ask, "Which one is higher". But try adding in the tiniest bit of complexity, say, put the two different notes in the middle of a chord and suddenly most people will no longer be able to tell what is different. Most people listening to a chord can't even sing the individual notes of the chord, let alone pick out whether it is tuned to just or equal temperament.
But to return to the context of the original point, which is that most serious piano players are going to value an electronic keyboard that can adjust tuning systems a lot less than an acoustic instrument that just... Sounds better. In most musical contexts featuring keyboards you need equal temperament anyway, unless you're expecting the pianist to update the tuning system every time they play a chord with a different root. I'm not going to argue that well tuned music doesn't sound better, but it just isn't pragmatic for piano in most contexts.
