The mythical "anabolic window of opportunity" has already been debunked. There is no need to hurry up and chug down an protein shake post workout as long as you have had an adequate protein rich meal within a 4 hour span. If its been 4 hours since then, then a fast digesting whey would be optimal. Muscle synthesis and breakdown is constantly taking place and involves numerous complex cascade events. The "adequate" amount of protein intake varies by person anywhere from 0.5 to 3g/lb, with 1-1.5 being a good average. Consuming more protein will not increase MPS. So while you may think that they are eating like crap, and under in protein macros, they may in fact be within the range their body is requiring. As for their increase in strength, this is fairly common in new lifters. Once your body adapts it becomes harder to build new muscle and increase in strength. If strength is your primary goal your training protocol will be more selective. A powerlifting workout is very different from a bodybuilding one. Some people are also genetically gifted and need hardly any stimulation to put on size, while others are "hard gainer" types with varying distributions inbetween. You should analyze what your primary goal is (strength, hypertrophy, etc) and focus on yourself. Leave your ego at the door once you enter the gym and forget what others do or look like. Lift with good form, work the muscle not the weight, and you will see improvement over time.
-Cheers