Anonymous ******************
@Travelling *******
The poster is asking for actual consequences... The actual consequences could be a fine of THB2000 for not filling the 90-days report with high chances to happen should the person goes to immigration office for documents. And as you said, low chances when crossing the border. So far, the topic isn't much covered on this group because the DTV is pretty new and people aren't much visting immigration office or do already report as per the law.
As I also mentioned, there is a 7 days extra allowance for filling it after the mentioned date. The poster shouldn't then worry too much for being slightly late.