Spotify and Bootleg Recordings

Spotify, and other streaming services, are supposed to offer legal “alternatives” to file sharing. Yet are they fully legal themselves? Search briefly for some of my favorite non-classical artists, I came across a number of bootleg recordings: the first two albums shown when you look for music by the Grateful Dead, and the first two albums listed by Bob Dylan. I haven’t searched too many artists to see what other bootlegs are in the Spotify collection, but the presence of any bootlegs makes me question how such a service can claim to be honest.