Well a few reasons. The airfield (KOZR) is incredibly busy with IFR military student traffic. For efficiency sake, it helps to have everyone on a SID. ATC doesn’t ban radar departures there but unless sticking in the local GCA pattern most are going off on the SID. Second, obviously being a IFR student training base, doing a SID has important training value. Finally, we were all /U when I was there, so the SIDs were usually taking us to our first fix / NAVAID on the way to the enroute phase anyway.
Ironically, KOZR is used a SID filing example in the GP. Probably been in that FLIP for 50 years.
View attachment 77527