What cost more making drugs or paying for them to be in and out of prison plus medical costs? Plus switzerland said it was a success and they helped lots of people get off the drugs. Plus the ones that were using the program started to become part of society again, since they didn't have to pay for drugs they could start working again and going about their day. Then pop in for their fix and get back on with life, while the staff there start working with them.
You forget the mentality of the US vs Switzerland. That wouldn't work over in the US because of the different (not better or worse) belief system.