Market economies are not built on demand. If all you have is demand then you have a failed economy because you will have runaway inflation the vast majority won't be able to afford the things they need
Which is precisely what's happening in Canada. The housing market has exploded because there's demand but not a sufficient supply. The strain on the medical systems is similar, demand increase faster than supply
Essentially you got it backwards. The magic in a market economy is the supply, and it is the nature of section economy that supply will appear to try and fill in demand. Loweskilled glow paid workers artificially ruin that dynamic and demand winds up outpacing supply with disastrous results
And their wages are too low because they're not worth anything. The system operates on the concept of being paid a dollar for the creation of a dollar's worth of value. To create higher value you need to have skills and abilities or assets which allow for that and that is exactly what is leaving Canada