An article on BBC News entitled "Why rent control isn't working in Sweden" reports how insufficient stock of rent-controlled apartments in Sweden and especially Stockholm has led to a housing shortage. Once secured, a rent-controlled apartment is for life in Sweden. Sometimes it will be passed between relatives or friends or sub-let at a higher rental (although regulation is intended to prevent the latter). It seems that flat-shares are not common and that there are few private letting agencies given the focus on rent-controlled properties.
The private rented sector and insufficient housing supply (a Europe-wide problem) has produced the house in multiple occupation (HMO) model in the UK whereby a residential property is let to persons occupying in more than 1 household who share some basic amenities. The definition of an HMO is a residential unit occupied by 3 or more tenants not as a single household and with shared basic amenities such as a bathroom, toilet or cooking facilities. The standard of HMO accommodation is regulated through the HMO licensing regime (read my article summarising the 3 types of HMO licence: https://realestate.howardkennedy.com/post/102h5iz/a-place-to-call-a-house-in-multiple-occupation-westminster-city-council-introdu). Market forces set rental levels and HMO acquisitions are popular with buy-to-let investors because of their income-generating potential.
As a lawyer acting for investors in HMO portfolios, it is interesting to contrast the Swedish rent-controlled landlord and tenant property model with the UK's private market generated HMO. Each cater for affordable housing demand and each will have their drawbacks and critics.