A celebrity is a brand.
That brand is marketed to generate revenue, by using that brand to endorse products or services.
By providing royalty-free, commercial use, photography you are asking that a celebrity grant the right to use their likeness to promote anything anyone wants. They don't do that for very good reasons. Suppose the celebrity has publicly taken a hard stance on animal cruelty. Do you really think they'd want any animal testing facility to be able to buy a stock image of them and use it in their advertising??? Of course not. So, they protect their brand by not distributing any royalty-free commercial use images.
Since the brand is a person, celebrities customarily want to know what is being sold before they agree to their likeness being used. This also often comes with a fee. A fee customarily much higher than any royalty-free stock service charges.
If you wish to use a celebrity likeness to endorse a product or service, you need to research and find the agency managing the celebrity and then contact them to negotiate an endorsement deal.
You won't find "royalty-free commercial use images" of celebrities anywhere. All commercial use celebrity images would be what is referred to as rights managed images, not royalty-free.