Every country in the world requires you to do a report every now and then if you're a long stay foreigner with any kind of visa. This is not exclusive to Thailand.
If you managed to bring it in the first place then no, they would never find out.
Then again, why are people so afraid of taxes? If they already paid taxes in their own country, you can pass the receipt for deduction or even exemption.
I am a digital nomad for the past 5 years and I wouldn't even consider taking long term visa unless I really know what is real daily life like at the place I choose lmao.
You need a reality check, taking long term visas meaning you will have to live in Thailand for months on end. If you didn't even know and like the place enough to even consider living (renting a place, paying bills, doctor visits, buying groceries, etc) why bother getting DTV? Might as well visit and be a tourist for few weeks and move onto other places to visit.