The pennies in the tray are explicitly put there for you to take one. The DNS server is not there for you to avoid paying for the internet service you're using.
It's a small thing, and I don't personally think it's a big deal to steal wifi, but the idea that because something is easy to steal means it's not theft is ridiculous.
As a tort, doesn't theft require that you're taking someone else's property and depriving that person of its use?
Using someone's bandwidth surreptitiously isn't really "theft" as much as it's virtual trespassing. Just because you're checking your mail doesn't stop someone else still using the connection (or even blocking you with a single click).
the idea that because something is easy to steal means it's not theft is ridiculous.
I'd agree with that, but I don't think it's "theft" (so my counter examples were poor, I'd admit ;-)). It's more like someone jumping in your swimming pool without permission, rather than actually stealing the water.
It's a small thing, and I don't personally think it's a big deal to steal wifi, but the idea that because something is easy to steal means it's not theft is ridiculous.