It's really like nuclear energy or even nuclear weapons. It's a tool. When a meteor starts descending on Earth you are not going to kill it with C4. Without nuclear power plants large portion of the world would be in dark. A tool will be used in different ways by different people.
how can we stop corrupt people coming into government in the first place
Corruption is only possible under an altruism. This is a radical claim and I've removed the raw power aspect for ease as the presence of power permits abuse without a need for corruption(Like a child playing with ants). When a society shuns altruism, there will be many capable people willing to screw the other guy by providing a better service to make a buck.
A person would become less corrupt for his/her own financial gain (kind of a moat/purple cow) and corruption will be raced to the bottom. There can be perfect people but not perfect systems. Human actions cannot and shouldn't be controlled; only incentives should be.
People would pay a premium for convenience. But under altruism this wouldn't work that way. I'm living in a developing country with free healthcare for everyone. But private healthcare is free to compete. The result is that only poor people and middle class people facing expensive surgeries use the public system. People would rather pay up than bear incompetence/inconvenience whenever possible and the entire private healthcare system is built upon this. Even the people who use the free healthcare generally speaks ill of it and praise private hospitals and wish they had enough money to afford that.
Private hospitals have a good name only because they want to make a buck and give a very good care and treat patients really well. The doctors or the staff doesn't neglect anyone and these hospitals don't have a great track record and good public perception compared to free care. (Still, people hate the expenses. But they bear with it)