You remind me, MonctonRad... a not-quite-first-world thing about here, I suspect, though I wouldn't be surprised, and would be pleased, if someone mentions it's also the norm elsewhere in Canada:
Neighbour had pest control visit again when she came downstairs and there was a housecat-sized rat in her kitchen, and he finally told her, "If you block up all the rat holes in your basement, they'll come up into the house. You need to leave them alone in the basement or crawlspace, they have highways throughout St. John's. If you leave that alone, they'll leave you alone. They're not coming up into the house, they're going from parks and lakes to the harbourfront and anywhere the sewers are broken underground."

Which, for financial reasons, is what I've been doing. I don't have a basement, only a care crawlspace with old foundations and chimney bricks and bare earth. It's only a few inches high on the uphill side, but there's room to stand up (probably 6-8 feet) of space on the downhill side.