I believe the landlord can only do so much. A landlord can't guarantee a tenant will never leave crumbs on the table, and the apartment will never get messy from tenants' belongings, and the pet food stored in airtight containers and sitting out in dishes all day. They can't control if you go to a friend's place or the movies and get fleas on your socks and carry them into your house, or ensure that you have checked all boxes and furniture for cockroach eggs.
It's impossible for a landlord to micro-manage every little part of the tenants life and make sure they never bring in cardboard boxes and give weekly inspections and control every little thing...THAT is the real part of pest control. And THAT is actually the tenant's job. The tenant needs to take responsibility for how they live. Sorry if this is a rant, but I just had this come up recently, and I'm not going to spend hundreds of dollars on professional pest services when the ants will be back in 2 weeks because the tenant leaves out pet food all day.
So there. Tenant's responsibility.
P.S. Try the little Terro trays, they kill within days, but if there is a food source they will be back.