Taking the bus to Javits Center will quickly show how even NY with their subways and buses fall short. I ended up walking about 10 NY city blocks b/c the bus wasn't running.
I won't excuse Javits: they built it in one of the most inconvenient neighborhoods in Manhattan for public transit (presumably because it's a convention center, meaning that most of the expected traffic is out-of-towners staying at nearby hotels). That being said, the 7 to Hudson Yards is (IME) the best way to get there, and is among the more reliable subway services.
Edit: That being said, 10 city blocks is half a mile. That's an ordinary walk in NYC.
