Bezos doesn’t seem to have that problem.
More to the point, people have accepted Amazon as a growth company. So long as Wall St likes the story, the price goes up, everyone is happy.
On the other hand, AMZN is trading at ~230x earnings and ~4.6x revenue. For comparison WMT (Walmart) is trading at ~30x and ~0.5x respectively. Amazon is growing much faster, but there are no guarantees that it will do so forever. To reach ratios like Walmart's it will need to take in ~$3.8Tn of revenue.
For comparison, their revenue in 2017 was $178 billion, and in 2013 it was $74 billion.
It’s not entirely unreasonable as Walmart’s total revenue today is $0.5B.
(2 trillion dollars seems like a big correction to me, btw)
Similarly, if you buy shares in Apple, you do not directly own its cash, facilities, intangible assets etc. Apple owns these. But you own voting rights and the ability to participate in dividends or buybacks.
In both cases the company -- the company's management, really -- has a wide degree of freedom in what it does. Apple can buy companies or sell iPhones without consulting shareholders. ETFs can buy and sell shares similarly.
Similar-looking but quite distinct is the trustee/beneficiary relationship from trusts law. In that case the trustee legally holds property "for the benefit of" the beneficial owner. Again, as a beneficiary, you would not own the shares held by a trust on your behalf, but the trust would need to buy and sell them according to its view of your best interests.
Since both corporations and trusts have wide-ranging legal, financial and taxation implications, the details vary widely depending on where you are. Each jurisdiction has comparable but distinct caselaw and of course legislatures have tinkered quite feverishly with it too.
I am, of course, not a lawyer. I didn't even finish law school.
https://www.bloomberg.com/view/articles/2018-01-30/iss-tells... has some useful pointers.
Amazon's operating income is up to an annualized $10 billion now. Their profitability has exploded higher in the last three years (thanks heavily to AWS), drastically out of ratio with their sales growth.
Another three years from now, their operating income will very likely be up to $20-$25 billion (I'm using operating income here because of recent rule changes on what's included in net income). That would still be a rich multiple on today's market cap, no question. There's a massive gap between AMZN having a 40 or 60 PE ratio (ie a very rich multiple), and your claim that they'd need ~$1.5 trillion in revenue (Russia's nominal GDP for 2017) to justify their valuation.
Amazon's net income margin now exceeds Walmart's and is heading higher due to the fat margins of AWS. At $400 billion in sales (five to seven years out), they'll very reasonably be able to generate $30 billion in net income (old net income calculation) on the path they're on. At $30b in net income, you're talking a ~30 PE ratio at today's market cap (ie a traditional valuation), and it requires nothing even remotely like an equivalent to Russia's GDP. Microsoft and Google both routinely sport valuations that are 30x multiples of earnings (as do dozens of large tech firms). The issue with Amazon, is that their future returns have been pulled forward, not whether they can ever justify a $900b market cap with a traditional multiple.