just read the laws and guidelines about visa exempt and what is mentioned at MFA websites. The limitations are directed to IO's and visa exempt just is not made for long time stay.
depends on what you define as abuse, visa exempt is for short time tourism, when you use it in any other way, that is abuse. In that case you use the fact IO never can check all entries.
Thai prepaid sims do have an expiration date, but when you top-up it will be changed, at True you can also for a few baht set the expiration date further in the future to keep the number when you are away for a long time.
For True it is the same, I still have my first SIM, just top up with the package I need at that moment, sometimes even with roaming for neighbouring countries, because I'm too lazy to buy a sim for jus a week in another country.
Where did I say the people in charge of deciding about a visa are stupid, that are not my words , but yours.
You can renew in the country only once, that possibility is indeed made on purpose.
When it was meant to stay longer they would have made it possible to extend more often.
The very popular borderbounce is the loophole, that is what we are talking about here, not the in-country extension.
And yes I am aware that when I stay in Thailand over 180 days a year, which I certainly would not do, I would become tax resident, but that is totally unrelated to DTV and this topic, and that is certainly not general for each country as you seem to suggest.