there's no subway in Thailand. Try and keep on topic. Fyi you can use cash in Thailand. If immigration want proof you have funds then make the effort to go to an ATM before boarding the plane. If you want to make a big deal about it and claim cash is never used, then best not to travel.
who won't take cash? No idea what you are on about. You can't show immigration a credit card. They need proof of funds. I used cash wherever I can in Thailand, I avoid cards because it costs the restaurant extra %. I like to eat local and at street stalls so would never use a card. Cash is king.
that's not new, retirement extension requires money in bank. The initial visa can be applied for outside of Thailand with non Thai bank account. Then enter and get a Thai bank account.