Soaps and shampoos are a bit of a luxury item, which is why there are whole stores like "Bath & Body Works" that just sell them. It's a marketing opportunity for the manufacturers to pay hotels to put out their mini-bottles for free. There's no such niche for boutique toothpastes.
I'd be rather surprised if hotels routinely got their mini-sized bathroom products for free. In the case of the big chains, they mostly slap on their own house brand anyway.
But, yes, there's at least the opportunity for boutique hotels to use a "luxury" shampoo/soap brand as part of their overall image and guest experience.
Whereas for toothpaste, it's pretty much Crest or Colgate. Or, if you're a somewhat frou-frou B&B in Vermont or California, maybe Tom's.
