When you buy a share in a company, you own a slice of that company. You have voting rights, access to shareholder meetings, annual reports, bod meetings etc.
What that share is worth is what others perceive it's value. what it's market "worth" is completely irrelevant to the fact you own a share.
In an increasingly large number of companies even this notion of a vote is a facade. For instance at Facebook and Google, Zuckerberg and Larry/Sergey would maintain majority control even if you bought all the stock on the open market, because of stock tiering. So when you buy stock in these companies you're practically not even buying a vote. I mean you technically are, but it's like participating in an election of with 100 other people, where one guy gets a vote that magically counts as 101 votes.
That why things like the occasional 'share holders look to force Zuckerberg out' type articles are 100% clickbait. Google and Facebook also even tried to force scenarios on shareholders where the real owners of the company were going to "sell" their shares without giving up control by introducing non-voting shares. These plans were only stopped thanks to the courts because they, of course, passed a shareholder vote. [1]
[1] - https://arstechnica.com/tech-policy/2017/09/shareholders-for...
Facebook also demonstrates it - Zuckerberg and a few others (many of whom have given him voting power on their behalf) own 'Class B' stock, which is worth 10 votes (and thus could reasonably be treated as each share being worth 10 of Class A shares). What is sold to everyone else is 'Class A' stock worth 1 vote. Despite owning fewer stock shares, then, Zuckerberg has more votes and thus has effective majority control.
You mention due to stock tiering, but that's just it, those tiers don't remove votes, or even owning a share of the company (your stock still does), it just ensures that majority control stays in the company's control. It doesn't change the claim that stock shares = shares in the company. It just changes the percentage each stock is of the company, so it's not as simple as 1 stock = 1/(# of outstanding shares) control, but it still is (100% stock) = (100% control), and (X% of voting power from stock) = (X% of control).
the stock exchanges really missed a trick by not prohibiting this sort of bullshit