If you use the advanced one on the site it gives reasons as to what your mistake is, which is helpful.
I use it when I need to proof read other's work, catches the stuff you automatically fix in your head.
haha not quite. I'm a remote developer and I live in South East Asia - so travelling all the time - and I feel safer when I use a Secure VPN to book Airbnb's / flight tickets etc as opposed to sending credit cards over a random wifi connection - I know unlikely with HTTPS, but still.
Also, occasionally hotels block some ports, including port 22 which is the holy grail when I try to commit code to Github.