Democracy doesn't mean "everyone shall vote on everything". Voting is restricted to a specific series of things or a certain nature. How to run a private business is not one of them.

There are fundamental differences between a company and a government, one can't just say "a company is sort of like a small government".

Nevertheless, in capitalism people are free to create businesses run by "democratic" vote of its members. Usually that doesn't happen simply because for most scenarios such a system turns out to be less efficient, meaning other companies are better at satisfying the consumer.