TL;DR chronic underfunding of the system, here's one example article:

https://www.cbc.ca/news/canada/toronto/ambulance-response-ti...

The federal government shifts the responsibility to the provinces, the provinces in turn try to download as much as possible onto the cities. There's not enough money for everything on every level of the government.

This also reflects on 911/dispatch systems, where there indeed might not be easy visibility of when an ambulance might be available, and even then it could be preempted by a higher priority call -- although a heart attack has to be close to the top of the list.

There are also occasional weather events, like the storm two days ago, that cause a surge in demand (>300 crashes reported and many of them needed attending to).

Healthcare is one of the exclusive powers of the provinces, as laid out in the constitution. There are things the federal government can do, such as provide money, but provincial leaders complaining about lack of federal involvement do so in bad faith; they would certainly complain louder if the federal government overstepped their bounds. It's worth pointing out that taxation and borrowing are also constitutionally protected powers of the province.

> The federal government shifts the responsibility to the provinces

It's not a 'shift'. Healthcare has always largely been in the hands of the provinces.

The federal government funds research, distributes money from have regions to have not regions, and sets federal standards, but the actual spending of money and provision of services is in the hands of provincial authorities.