I think it depends on what is meant by "landscaper."
If what is meant is someone who designs garden plantings and trees, etc, yeah, that's a pricey service.
On the other hand, if what is meant is someone who mows the lawn, strimmers the fencelines and hauls debris, that's something that I can get done for less than $100/day.
Different couples run their finances differently but I don't think it is unreasonable to think that in a household with an annual income of around $100,000, that a couple hundred stray dollars would go unnoticed.
Besides, Kaine may very well have known about the landscaper's legal services and not known about any alleged illegal services being solicited. If you see what I mean.