The reality is far from that, though. Roughly a third of the citizens of the US would have to go into debt to secure $3K on the spot, they don't just have that laying around in the bank. Doing so could easily cause a downward spiral where one would have to choose between basic necessities or moving back in with family for months or even years to pay back the debt (I know because I've been there).
Hell, our household income is nearly $70k and while we do have enough in savings to cover such an emergency, it would still be painful and it would take us months to recover the money. Thankfully we both work for local government and have decent dental coverage, but it's a far cry from the much better health insurance we enjoy.
Also, the idea that major dental surgery is "just" $3K is amusing. My bill for removing my wisdom teeth came to nearly $12K, of which my insurance paid all but $800 thankfully. That wasn't even the total cost either; I developed a severe infection and when I called my dental surgeon he told me to go to the emergency room (another $1200) to have it drained and get an antibiotic prescribed. The emergency room gave me the antibiotic but told me to go to the dental surgeon for anything else. It's a total clusterfuck.