It's the Military Academy that gives +1 SOC on Honors, not regular University, just FYI.
Yeah, I misread it while scrolling around. My bad. SOC can rarely increase in University from the event roll, though.
Entertainer, NAVY and Scholar are the three that have SOC as a PD option. Navy was always the traditional ticket to aristocracy in Traveller.
Entertainer has so many shots at +SOC in mustering out that I doubt many would be rolling on PD just to get it. Jack-of-all-Trades and +INT are the prizes on that table. Plus they get SOC +1 at rank 5, too.
To me it seems that it shows soft power and intellectual achievement are held in higher esteem than even high military rank (and it IS worth noting that below command ranks the soldiers get no more social advancement than a blue collar Citizen or a Free Trader). We KNOW that the default culture is aristocratic... the relative social immobility of grubby commerce ,ight suggest that by the Far Future they've gotten savvy to the real worth of the business mindset? Or that it's a bit like Feudal Japan where the social order was Nobility > Farmers > Merchants
However, I'd also note that Corporate is one of only three careers with SOC as their Survival roll (the others being Artist and Dilettante). So characters that are low SOC generally do not last long. At least Artists DO have a way to build up SOC; aside from PD, there's an event that can increase it. Middle class Suits (SOC 6-8) still have to be a bit lucky to last long enough to get to CEO. Mostly, those jobs are going to go to characters who started at SOC 9+. The Army may gatekeep the plebs from officer grade, but Management isn't even keeping them around long. Back to real work, scum!
Oh, and for careers with +SOC in the 7 roll, there IS another way to access it other than high rank. Some events grant bonuses to a Benefit roll.
That can happen in Agent, Army, Navy and Noble. Doesn't matter for Scholar as their +SOC is mid-table, but it can increase the already high chance of +SOC for Entertainer.
It does appear for how you LOSE SOC and other text that it definitely includes positive fame and acclaim.
To me, one thing that is clearly missing (and the omission is really a CT legacy) is a discussion of SOC changing after prior career generation. It's certainly not unheard of for PCs to gain fame or notoriety. Small scale wins and losses wouldn't be important, but especially for characters who leave prior career with profile, any big things that happen to them next would get noted if widely known about.
The text box on CRB p11 pretty much pegs SOC to fame, at least in part. The definition on CRB p9 simply says "A Traveller's place in society."
During prior career generation, you can lose SOC from disgrace or dishonour (though those events tend to be in the careers where SOC can also be gained. Even being sent to prison does not automatically lose SOC, though some events that reduce your SOC do send you to prison as well). Back in OG Classic Traveller, the Other career actually could reduce your SOC just by doing personal development...
So... a Referee would be well within their rights to impose a reduction or an increase in SOC if campaign events led to that.