Can a foreigner on a Non-O or spouse visa in Thailand switch to a work permit without leaving the country?

There are two steps of change from O-dependence to B. (Immigration name “change the reason of stay”) if current immigration location same with new employer location you can do it all in a day.

Step 1: cancel (or cut) Non O by submit a letter from current visa sponsor with the reason of cancellation. (spouse company). You are able cancel visa 21 days before end date. e.g you want visa ending on 30 Dec. you can cancel it since 11 Dec.

Step 2: Apply Non B by providing your employer documents which contract or offer letter, letter to immigration and other general paper. Make you your visa valid at least 15 days or above.

In case of difference location after cancel visa within 5-7 days you should apply Non B at new location

My wife switched from a non-O dependent (extension of stay) to an extension of stay for work without leaving the country. She's a teacher and they have been given permission by the powers that be to switch in country.

Assuming your wife's employer effectively sponsor your visa, they would need to work very closely with your new employer to sort it all out. You would need go cancel your current extension of stay but don't do this until your new employer has all of the paperwork needed at their end.

I'm not aware of any other professions being given this 'permission' mind.

It depends on where you are in Thailand. Some people have reported success transitioning to a Non-B inside the country. My advice would be take all the paperwork from your employer, go down to immigration, and ask how to transition to a Non-B.

You cannot work or obtain a work permit on a Non-O based on Dependency though.