Yes DDP means Delivered Duty Paid which is how Lazada operate; they show a shipping/delivery cost which encompasses all aspects of costs from EXW to DDP so you don’t have any issues with VAT/Customs/Duties etc.
But she clearly says she will return from Bali to Phuket, then to Bangkok to fly back to Canada, utilising the return ticket she entered on. She needs nothing else.
I doubt it, especially when their base country - Dubai/Emirates, for example - have removed the requirement. Also, for an airline to insist when others don’t will certainly affect their bookings..
How many IDPs actually have a Thai translation? My one issued in S Africa didn’t.. Regarding the ‘3 month validity’ - it’s not a driving thing, it’s an insurance thing: some companies won’t issue cover, which is their right.
The company should have to obtain a court order for the debt - which is unlikely due to the small amount - and for them to apply for you to be placed on a banned list seems a cosmic overkill, even if they could. I hope you will enter the country, honour your obligation, and make good.