I was surprised by that too. The old school method was to cast animal friendship and run it as an NPC creature.
You can use assume a basic level of master-companion control and require Wis (Animal Handling) checks for challenging actions. Also, use speak with animals and beast sense when needed. It forces the druid (or hunter-ranger) to use their magical abilities to maintain one or more companions and use them effectively.
But that might seem a little unfair compared to best master-rangers, paladins, and wizards. Alternatively, you could add find familial to the druid (and possibly ranger) spell list and allow a broader range of animals with the stipulation they are not extraplanar spirits in animal form, but natural animals of their type.