Its not the parties.
Its what Canadians want.
They are voting for the NDP and LPC knowing full well what spending they want.
The CPC also gave up being fiscally conservative last election. Until canadians prioritize paying down the debt, political parties will continue to push the envelope.
Its likely due to seeing all that spending and no obvious repercussions. Harper spent hundreds of billions, no higher taxes. A few marginal servoce cuts to bring in a balanced budget which allowed Trudeau to come in and say he was willing to defecit spend and suddenly Harper was out and Trudeau was in. Trudeau has not posted a surplus, but again, no higher taxes.
Back when deficits obvious repercussions Canadians seem to have payed more attention to it. How often does the debt/deficit make this list as Canadians top priorities?