As far as I know, the loophole in the law is just that. It is not illegal which is why it is exploited. This crackdown did not just 'reach' these two Provinces but is aimed directly at them since they have a large community of non-Thais resident many of who will hold their land plots and commercial sites in the name of a legal Company.
In case you think I am defending my own position my accommodation and land is owned solely by my Thai wife and we have been happily married for 47 years but lived in sin before marriage.????
More likely the authorities are chasing commercial businesses because prosecuting residential domestic owners would result in a significant impact on local ecomomies and scare off potential retirees.