Netflix feeds you UK choices because it reads your internet connection as being in the UK.
Your DNS settings are what identifies your location and country. You can sometimes manually change the DNS settings or pay a few quid a month to something like Unblock US which fools Netflix into thinking you're in the US for you.
lolwut? that's not how those "unblocking" dns services work. They work by redirecting region restricted websites (eg. netflix) to their proxy server. That has an advantage compared to VPN because it only proxies the traffic that needs to be proxied.