From a landlords perspective Homes\Houses of Multiple Occupancy give a much higher return than single residency; from a financial perspective it is generally a no-brainier. On the flipside the hassle involved puts many off, and many don’t do it twice!I see what you are saying 100% I suppose its different in different area's any house that pops up on this estate is sold within a couple of days, a wrecked house like ours was before I rebuilt the place is going to knock you for 150k bare minimum & there is not many young couples just starting out that can afford that + the refurb costs due to the reduced wages in the area bought about by the influx of cheap migrant workers
One house directly over the road sold a few months ago & has been fully refitted from the roof down with extensions to the back & side & I know the builder had at least 40K off them add that to the purchase price (175) & none of the 6 en suite rooms in there are going to be cheap yet it was full within 3 days, such is the shortage of housing in the area
as for new builds, investors snap them up as they are really easy to rent out, demand is high and accordingly there is a premium on rent. Those factors are driven by the renters, not the landlords. The fact that they usually only require minimal work to prepare for renting also makes them desirable to investors And developers like selling to investors as they are usually very quick transactions.