A better analogy
SDN is like writing a custom application rather than using one off-the-shelf (with plenty of semi-custom ground in the middle). There are huge, massive downsides in terms of costs and resources for developing and maintaining custom applications for a business - but sometimes they still come out ahead in terms of benefits, especially as companies get larger and the costs shrink in terms of percent of revenue.
I have a slightly different take on the drunk driving problem: that it's one of economics. Governments set the price of lost life due to negligence at an absurdly low rate. I'm not sure about other countries, but here in the states DUIs are an industry: you get caught, pay about $10K in fines and legal fees, higher insurance premiums, have some meaningless probation, and you're out on your way. If, heaven forbid, you kill somebody - you do a year or three in jail (plus fines and legal fees). So the state is making money, the lawyers are making money, the prison-industrial complex is making money, the insurance companies even wind up making more money, and the victims - eh, whatever they can squeeze out of the insurers, which is not much. A better system would be to garnish 50% - 75% of the killer's wages for 10 years or whatever and give it all to the victims. That creates a far higher incentive to not drive drunk, but it will never happen because it doesn't benefit all of the highly-connected groups making piles of money in the DUI industry.