it is up to Thailand to define. If they dont want more than 180 days per year as a tourist, then list it as a restriction. Why make entry so unclear. List the guidelines and we can all follow.
Thailand can make any restriction it wants but it should be posted as an official guideline and not randomly enforced. Entering Thailand should be consistant regardless by land or air.
first of all, you can disagree with someone without being so rude...it would be logical that a 62 year olď who has a son working Thailand would not have issues BUT Thailand is not logical...the prevailing opinion is to get an OA visa before she arrives and that is her best option.
very good advice. Also beware that many travel insurance policies do not cover motorbike accidents...have her check her policy and make sure she inderstands the high number of motorbike accidents among locals and tourist alike