I always thought it was a good representation of who you might find riding the Subway. A mix of Anything Muppets, a few established characters (and one of the few times you'd see Bert without Ernie), and a sleepy-eyed cop!
And if you want a taste of what Sesame Street/ life in New York in the 70's was like, it doesn't get much better than this
The only thing that's changed in the last few decades is you buy a MetroCard instead of tokens. But the rest is still magically preserved. Step on a train, and you'll see your share of old ladies, Greenwich Village hippie types, sleepy-eyed cops, and if you look hard enough, you just MIGHT find Bert too (a long shot, but not impossible)