^{Update by Mega_Spud:}
Summary:
Teleporting an entity with the /tp command should match the target's rotation to the one running the command. This issue was partially fixed in a recent beta (for armour stands), but according to users the fix should be applied to other entities as well:
 
Repro steps:

1. Teleport an entity to the player using the following command:
   /tp @e[type=...] @p

Observed Results:
The /tp command does teleport the entity to the player, but doesn't rotate the entity to have the same rotation as the player
 
Expected Results:
The entity should have its rotated changed to match the player when teleported

Screenshots/Videos attached: No

Notes:

Original Description:
The /tp command does teleport the armor stand to the player, but doesn't rotate the armor stand to have the same rotation as the player:

/tp @e[type=armor_stand] @p