I have more than four reasons, but I won't go through all of them. I'll pick out four, as you requested.
I think our number one problem on the tax side is the high marginal effective tax rates. They kick in for people up to about $50,000 in income. I know we instinctively think of marginal tax rates as being bad for high-income people, but they're much higher when you take away the social benefits at low incomes, usually higher than 60%. So there's very little incentive to upgrade your education, take second shifts, and look for a better job and what not.
I would say that the employment insurance system would be number one. There's been no study that I'm aware of, or none with any credibility, that hasn't said that this is a disincentive. It subsidizes people to stay where the jobs aren't, and discourages them from going to where the jobs are.
My third one would be immigration. We're within a few years of having 100% of our population growth being determined by immigration, so the economic welfare of immigrants will largely determine the economic welfare of the nation. That's a very sad story, and it has been for the last 20 years. The problems go through the whole thing--the design of the system, the administration of the system, the integration of immigrants.
My final one is a remaining problem, not in the federal jurisdiction but largely in the provincial area. We talk about the high rates of taxation on capital, and largely they're provincial. We still have provincial internal barriers to trade. We have overlapping jurisdictions. One aspect that I particularly appreciated in the spring budget was Mr. Flaherty's use of some fairly harsh, bold language to say that if we want to get our productivity up, we need some improvements on the provincial side, not just federal.