The opportunity cost of 1 sqm of street parking space is not 1 sqm of "living unit", but 1 sqm of land.
If 1 sqm of apartment is worth $7.5K/month, and average building height is 4 stories, that suggests 1 sqm of land is worth approximately 4 * 7.5 = $30K/month (minus value of the building).
16 will be 4 times that.
My note was not about "opportunity cost", it was about the (extremely high) "rent" that a parking space at 5 US$/hour represents compared to its cost.
If you buy a 50-55 sqm apartment/flat/living unit in Copenhagen, you spend roughly 400,000 $, you can possibly rent it for 5%/year, i.e. around 20,000 $/year.
If you can manage to extort 5 $ /hour (for 12 hours/day) for a parking space which is 1/4th of area (and is not a building) you get more or less the same.