Because you are told lies about your health system. Do not get me wrong, US healthcare is great for those who can pay, and those who have insurance when the insurance company pays out. But as you have noted, it is fairly crap for others.
I live in the UK and work in the NHS (our universal health care system). It has problems, but not as many as the US healthcare system has. Despite spending much more per head of population than other developed countries, the US has worse health outcomes. http://en.wikipedia.org/wiki/Health_care#Economics
Life expectancy and infant mortality figures in the US are worse than in other developed countries, despite more money being spent (and wasted) in the USA.
In the UK there are waiting lists for routine problems. Problems that can not wait are treated as emergencies. Also, in the UK, people can also have private health care. If you have suspected cancer for example, you are see within two weeks, or if appropriate, the same day.
I can understand Americans being proud of living in the richest and most powerful country in the world. What I can not understand is why Amercians settle for a more expensive healthcare system where babies die that would have a better chance of life if born in another developed country.
Beware loosing your job in the USA if you get healthcare through that. http://www.guardian.co.uk/usa/story/0,,2167865,00.html
Or retiring if you have become ill when covered by work based insurance. Not a problem in the UK.
When it comes to your drug though, if anyone tells you that you would automatically get in with a socialised care system, they would probably be wrong. Remicade is prescribed in the UK, but due to its cost, it is limited. People however can still fund its treatment themselves like in the USA. The difference is that unlike the USA, if you can not afford it, you still have a chance of getting it (for a maximum of $8 per month on the NHS, private fees if you fund it yourself) whereas in the US, you have none.