I paid cash for a flight at the airport in Lampang. It was a Bangkok Airways flight. I also booked a Bangkok Airways flight over the phone a couple of weeks ago as my laptop crashed and they wouldn't accept a debit card. They insisted on a credit card. The said if I booked on the phone and wanted to pay cash I would have to make the payment that day. As we were not going to Lampang until the following day I paid with my credit card.

Unusual, never had them refuse my Bangkok Bank debit card and I've flown with them a lot.

Yes.

In the last 3 years since I came to Thailand I have purchased over half a dozen air tickets here in Bangkok with Cash at the local Bangkok office of those airlines

Sometimes you may be lucky enough to find a discount for Cash offered at the airline office that you can not get on line.

Of course, you have to go there to find that out.

That is why they have taxis here in Bangkok.

A year or two ago I paid in cash for a flight my daughter made to Finland with this company at their K Village shop: http://www.bookit.co.th/