Because the housing market has mechanisms (such as leveraged landlords) that mean that the price of land tends to inflate up until a situation of equilibrium such that the price of rent is always relatively high in any city where land is somewhat constrained, because zoning is a thing, because most people cannot get mortgages and are as such not able to participate in the condo market, because the price of land is wildly variable for reasons of zoning, because real estate investors do not always operate rationally (for example, empty rental homes held purely as stores of value), because the type of housing affects the type of transportation used which affects which kinds of land is suitable for use as housing, because not all housing is created equal in function or in value, and so on.
Simply supply and demand is not a sufficient mechanism to explain the housing markets in cities such as Toronto.