Afraid of RMTs need to end.

[Shirai]

How do people buy gils without gettig caught?

While there is no completely undetectable way there are ways to stay "below the radar" so to speak.
How exactly, I cannot tell.

All the ways I can think of are all ways that raise alarm bells, on the other hand, why should RMT care what happens if a buyer gets caught. They have their real cash anyway.