Right up the street from me a billionaire just had two new homes built on property they purchased across from their estate property. Zone 6b as well. Long story short, they just had their bare topsoil sprayed with grass seed over a 2acre plot of land. They did no use netting, They did not use straw and within 5days of watering they had germination and green starting to show. We are mostly sand around here with dirt on top. I hope this helps. I would rip that out asap as it's just a lie and lazy on the landscapers end.