At least in the US, zoning laws and parking minimums have really restricted the ability of cities to build more housing in high demand areas. Look at how much space is wasted just for surface parking lots in downtown Denver, Houston, Austin, etc… Name almost any bigger city and soooo much valuable land is wasted on cars.
I also agree that real estate should not be used as an investment. If there was more restrictions around owning property in cities, that would certainly help. AirBnB/short term rentals are definitely not helping and should be heavily regulated/taxed.