Only just realised from this that MacBook Pro's no longer have an Ethernet port! When did that happen? You need to buy an expensive thunderbolt adapter. I can understand removing it from the ultra portable super-thin models but not from the top end professional model.
A $30 adapter for a $2000+ machine isn't what I would call expensive. It does make the machines a lot thinner though and normally, you don't need wired Ethernet any more. I easily reach 60+ MB/s now over WiFi, so for the times where I really need the additional power I don't care about having the additional dongle with me.
Also, the profit margin on those adapters is pretty astounding.