NAFTA failed in two respects, though Mexico benefited a lot.

1) Labour laws were not matched to Canada's/US. Mexico was able to get almost slave labour without the worry about 'real unions'. Unions were started by the companies and controlled by the companies. Nice eh?

2) Environmental laws were NOT included. So plants built in Mexico have no where near the same regulations as Canada/US. Check the pollution in Mexico City.

Tighten up just those two will put things a lot closer then they are now. 

Softwood lumber. Pretty easy one to fix. Have the lumber companies actually replant all the trees they cut down in BC/AB vs. just clear cut and walk away.