Why are boarding houses illegal?

Why are boarding houses illegal in some areas in Australia, boarding houses are not illegal in Australia if registered and compliant with council approval $5K to $10K, fire safety $5K to $10K, building code and tenancy laws, but illegal if unregistered, overcrowded, unsafe, without council approval, fire safety, or proper tenancy agreements, with illegal boarding houses fined $10K to $50K and closed due to safety risks fire $500K and overcrowding. Boarding houses, also called rooming houses with 3+ unrelated persons sharing 5 to 10 rooms $200 to $400 per week per room in house $500K to $1M value, are legal if registered with council, with development approval $5K to $10K, building code compliance BCA for fire safety with smoke detectors $1K, fire extinguishers $500, exit signs $500 and fire doors $2K, council inspections $500 and tenancy laws providing tenancy agreements, bond $800 and notice periods. Illegal boarding houses are unregistered, without council approval, overcrowded with 10+ persons in 3 bed house 150 sqm, unsafe with no fire safety, blocked exits, no smoke detectors, risking fire $500K and death, without proper tenancy agreements, exploited by landlords charging $300 per week per room $3,000 per week total for $800 per week house $2,200 profit, with poor conditions mould $5K and no maintenance. For example, illegal boarding house in Sydney with 10 persons in 3 bed house 150 sqm without fire safety, council finds and fines owner $20K and closes house, tenants evicted. So boarding houses not illegal if registered and compliant with council approval $5K to $10K, fire safety $5K to $10K and tenancy laws, but illegal if unregistered, overcrowded, unsafe without approval and fire safety, fined $10K to $50K and closed due to safety risks fire $500K and exploitation, with legal boarding houses providing affordable housing $200 to $400 per week per room versus $400 to $600 for 1 bed unit.