I had friends growing up who lived with extended family all in one house. They'd convert any space they could into rooms and house as many people as they could. That's not a situation that'd be allowed under rental agreements or housing laws but is totally fine as long as you own the house you're living in. Not to mention the nightmare of communicating with your landlord every single time someone moved in or out.
Similar for me: Before I got into tech, I bought a house on a fast food salary w/ a lot of help from housing programs. 15k of my 65k mortgage was subsidized! This allowed me to jump from a $650/month 2 bedroom apartment to a $550/month mortgage and house 4 children. An equivalent apartment would've eaten my meager salary alive and would have been untenable. Anything equivalent to the apartment I had would've not been allowed legally