For one, Most of things in Classic really do not appear that much of "Hardwork" to make. Because well nothing gets added or it comes way too slowly. Secondly there is Devs that do free voluntary work and help improve games 24/7 all over the place. Infact it is not really uncommon for games to put up a form in hiring devs for their games as voluntary work to help improve their game. Just like it isn't really uncommon for YouTube videos to use some NCS Music in their videos.