If you set the new '/ride' command to always ride the nearest non-player entity, it works but you can somehow dismount it and then keep dismounting it even after dismounted and it will always teleport to the same entity except sometimes (couldn't get it in the video) it would ride a different entity.

command: /ride @a[team=player,limit=1] mount @e[sort=nearest,limit=1,type=!player]