The present value of the asset's free cash flow. Classically, this was distributed via dividends. In modern finance, for all but the largest companies, it's distributed through M&A.
Control doesn't alleviate the duties, fiduciary and of loyalty, the controlling person has to its shareholders. An acquirer who only bought the votes would still need to act in all shareholders' interests (or face litigation). To have a free hand, and full access to those cash flows, an acquirer thus must purchase the whole company.
In most cases, the target company's stock rises because the acquiring company pays a premium for the acquisition, in order to provide an incentive for the target company's shareholders to approve the takeover. Simply put, there's no motive for shareholders to greenlight such action if the takeover bid equates to a lower stock price than the current price of the target company. [1]
If the buying firm doesn’t need approval from the Class A shareholders, what would be their incentive to buy those Class A stocks at a premium?
Supervoting stock usually converts into regular stock on transfer. For example, Rent the Runway says "future transfers by holders of Class B common stock will generally result in those shares converting to Class A common stock, subject to limited exceptions, such as certain transfers effected for estate planning purposes" [0].
Delaware law is also developed in protecting minority investors' rights [1]. (The situation varies from state to state [2].)
[0] https://www.sec.gov/Archives/edgar/data/1468327/000119312521... S-1, page 59
[1] https://corpgov.law.harvard.edu/2018/04/26/controlling-share...
[2] https://www.stimmel-law.com/en/articles/corporate-struggles-...
You, as an investor, want to save money for longer than one quarter. You want to save money for 20 years. So you'd like to avoid 80 taxable events in those twenty years, especially as you are just going to be reinvesting those dividends anyway. You want the law of compound interest working in your favor and then you pay taxes when you actually sell.
E.g. at a 20% tax rate say a stock pays a 4% dividend once per period and has no capital gain. Suppose you invest $1 and want to hold that for 2 periods, reinvesting the dividend and then selling.
Then after the first period you get 3.2 cents (after taxes) and you now own $1 and 3.2 cents. After period 2 you get $1.065024. Then you sell for a profit of 6.5024 cents (there are no capital gains)
But if the stock pays no dividend and has a 4% capital gain, and you hold for two periods, sell, and then pay the 20%, you will make 6.528 cents.