Originally Posted by
Endus
It's a feature. There really isn't a "schedule" for elections. While there's a set term that can expire, after which an election is automatically called, any non-confidence vote in Parliament forces a new election, and as we see here, the sitting government can announce an election as well.
Non-confidence votes are easy; if 50% of Parliament votes to support it, bam, election. And any budget bill failing to pass is an automatic non-confidence vote that calls an election.
The maximum term is 4 years (used to be 5 until 2007) before an election automatically occurs. Since 2007, only one Parliament has gone its full term. It's actually much less likely that a Parliament will sit its full term than that a new election will get called.
This gets really complicated, too. The Conservatives are actually in the middle of a bit of a leadership debacle, which is arguably why Trudeau is picking his moment. There are two sub-factions in the Conservative Party, the old Progressive Conservatives and the old Reform, who can basically be seen as "fiscal conservatives" and "racist bigoted xenophobes". They combined for political power, but there's a lot of bad blood in there right now, and the Conservative Party may be about to tear itself apart. Parties in Canada are a lot more flexible than the USA; the Conservative Party only dates back to 2003 (where the PCs and Reform combined). While they held things together through the Harper Administration, they've kind of fallen apart since, leading to where we are now.
Also, those pesky non-confidence votes and the fact that the NDP exist are a problem for them. The Conservatives won't get more than maybe 35% of the seats. The only way they win is with the Liberals and NDP splitting the rest of the country, with the Bloc Quebecois being a potential additional factor on that side (sometimes they're relevant, sometimes not, it's REALLY chaotic). Like, look at the 43rd Parliament, just having ended; there were some 211 seats between the Liberal, NDP, and Bloc, as compared to 119 for the Conservatives. Plus a handful of others. The Conservatives only held 1/3 of the seats. Harper's government never held more than 166 seats, and without any backing from other parties. While it hasn't been done recently, coalition governments are a thing; if the Liberal Party and NDP decide to form a coalition, their combined numbers would be compared to the Conservatives to see whether the coalition of Conservatives "win" the election and form the government.
Canadian politics have a lot more moving parts than the USA.