It's not one person, one vote, so it's not democracy. It's very explicitly plutocracy (rule by money) as the operating principle of voting power is one share, one vote.
Except there's also a bunch of companies with special dual class share structures, where the founder gets way more voting power than everyone else and you can't even buy your way in. A lot of tech companies do this. This is, functionally speaking, an autocracy.
If you want an actual corporate democracy you would need to assign voting rights to everyone working at the company, aka build a co-op. Co-ops are a great corporate structure in a lot of cases but you can't really raise capital that way because VCs all want on your cap table, so all the big companies wind up being plutocracies.
It's one share, one vote. And you have a choice: You can ask the company to pay you (ie. apply for a job there), or you can pay for a share in the company. Either way, the decisions are made by those who pay. And that can include you — anyone and everyone has the right to start a company and to employ others, anyone and everyone has the right to ask for shares in the company as part of negotiating compensation.
I employed a painter a few months ago, and I decided what colour the kitchen now is.
> It's one share, one vote.
This is just wrong. As kmeisthax mentioned, shares can have different voting weights - if any at all. Many shareholders have no voting power.
> I employed a painter a few months ago, and I decided what colour the kitchen now is.
Did you actually employ them, or did you buy a specific service?
Indeed, shares can have different voting weights. And that matters, if you care mostly about the corner cases.