Shut the window. Or get screens. Before I had (to have) cats of my own I drilled new holes in the latches to make the gap too small for a cat to come through.
Fair enough but how?
Leaving meat out all day with open windows is called an invitation. Why not put the meat in a cold oven, or in the microwave, to thaw?
"How" is the key here, but as I say the owners should not just accept that others should put up with this.
I usually leave meat to thaw in the microwave or oven (not powered), so haven't yet had an incident with food, and they have been coming in the house without food to attract them.
I think the best for now would be to put a notice in the mail boxes and place the burden on the owners, and if it doesn't stop I believe I'm well within my rights to safely drop them off at the SPCA.