"Lavish" isn't normally used for persons either.
If a couple puts on a lavish, bounteous dinner for friends, you could describe them as bounteous and lavish. But you'd normally use the terms for the dinner, not the people.
The dictionary you quote has this:
"He was always lavish in his praise of my efforts." Even though this says "He was always lavish" from which one could infer that "He is a lavish person", this is an illusion, a misreading. It is his praise which is lavish. He acted lavishly in his praise. In other aspects of life, he may be niggardly.