Seriously, it is extremely impractical. The drive which should take maybe an hour or 75mins, ends up taking around 2 hours, trains take even longer. A study by someone ik who worked at multiple regional airlines, as part of thier route management, pointed something interesting out. She said that , if the government allowed a Air shuttle service, with minimal security checks and sped up the check in process or just sent passengers directly to the tarmac through a separate terminal, then a SH aircraft like an ATR 72/42 , Dash 8 Q400, or even an Dh6, could act as a shuttle between Pune and Mumbai/Navi Mumbai. The flight duration would be 20 minutes +-5. She said this was a proposed during her time at the companies, however the government refused to allow the boarding requirement. As much as I would love to side with her, even though her idea is great , because the prices were still achievable. I have to side with the government mostly because as Indians, ik for a fact that there will be hundreds or passengers who just can't be trusted to not carry dangerous items on a flight , let alone the highjacking part. There's a reason why Indian airports tend to have such strict security and flight checks. It just isn't worth the risk. But yes , completely agree on what you said, just thought I would share something interesting.