the website you referred to is wrong, it talks about buying this "visa on arrival" in advance for eye watering sums of money. The attached provides the actual days, including from 1 October.
The fact you didn't submit tax returns, are 31, and single aren't going to see a tourist visa rejected. Most likely it's because you didn't submit flight details or didn't have sufficient money on your bank statements.
I don't know if they're issuing non-ED visas outside of Thailand in order to learn Thai except at a university maybe. I don't think any of the language schools are offering online classes anymore which will provide you with a non-ED visa, if they were then you can study it online in your own country.