Neither hearsay nor gossip!
Your friend was correct, at least in as much as although many of the soldiers do exist their salaries are minimal and many are re-employed as security staff, for example around Siam Reap - often by security companies run by the Generals you refer to!
When negotiating one inter-faction prisoner exchange in Cambodia several years ago I realised very quickly that the Khmer Rouge "Colonel" involved had never actually commanded more than 6 men: his second-in-command, a "major" was also his bodyguard, even though he had lost an arm* when he forgot to disarm a mine before moving it, and the remaining 5 were the only men in the small hamlet where they were all subsistence farmers. When I pointed out that in most armies he would be lucky to be a Corporal he laughed and said that would not impress his wife so much!
In Thailand the reality is similarly unimpressive, as despite having a similar sized Army to Britain, Thailand has more Generals than the British Army has Colonels. It is also relatively common practice for any Thai conscript who has completed his basic training (which is unavoidable once conscripted) but who does not wish to do any more military service to "sign over" his pay to his superiors and to only have to return to his unit at the end of his service to be formally discharged.
* : no jokes about "maybe he was an expert in unarmed combat" please!