Getty-Images* will barefacedly "license" you public domain images at significant cost (i.e. thousands per image.)

Worse, they've attempted to extract licensing fees from people who use such public domain images, in one unfortunate case: Carol M. Highsmith, a photographer who had donated her works to the public domain received a letter of demand from Getty Images for using her own public domain images.

https://petapixel.com/2016/11/22/1-billion-getty-images-laws...

* While Getty Images and Getty Museum are born of the same "Getty" family, they aren't connected entities, and one does not reflect upon the other.