Do you really think that requiring 4-year degrees and passing a licensing exam would make a big difference? The fact is that, outside of civil engineering which involves a lot of dealing with regulatory agencies, most engineers in the US don't have PEs. I started on the path to get one because, had I stayed on my initial career path, I'd have been sending blueprints etc. to regulatory agencies but I ended up changing careers.
How many individual engineers do you suppose get prosecuted for making errors--even careless ones? I'm guessing very few in the West. And I'm not even sure lopping off a head here and there to encourage the others is even a good idea.
I would assume that engineers, at least in the US, are far more concerned about getting fired/eased out than prosecuted if they do stupid things given that companies can do so pretty easily.
Would you say the same is true for a lawyer? Are they more worried about being fired from a law firm than being sued for malpractice and being disbarred? If not, why would engineers be different?
I would assume that being disbarred has a pretty high standard of misconduct as opposed to simply not making partner or whatever level of action makes maintaining employment at a large law firm practical.