Put away the Laffer curve stuff, it's a theory that simply doesn't apply here. Laffer's main premise is that as tax increases, incentive to produce and output decreases. I'm guessing you read some scholarly article that shows the breaking points for taxation and that that has you confused about the theory.
You are right the economy is chugging along nicely, thanks in part to the fact it never receded under the last regime, the US economic surge, and in part because commodity prices are back in the green.
That doesn't mean government is healthy, or that government finances are under control. In good times we ought to have a bountiful surplus. Imaging if you were a big company and you were loosing money and spending like a drunken sailor in a robust economy -- what would your stakeholders do at the next AGM vote?
The Laffer Curve does matter. While the original concept was part of the theory that cutting taxes could actually increase revenue (used for trickledown/supplyside economics) it has been tried enough that numbers have been put to the curve in more places than the two end points. What we see on the curve (not theory any more) is ~35% represents maximum economic growth rate and 70% is maximum revenue. We are currently below 35% any additional cut reduces growth rates.
As for the US, remember they have three times (and climbing) the per capita deficit and four times the federal debt per capita compared to Canada (Trump vs Trudeau). If deficits matter Trudeau (and Canada) is a superstar compared to Trump and the US.