Delta can't provide an equal level of service to an airline that is government subsidized and operates in a country that allows them to hire and fire employees on the basis of their looks, while making money, something that Qatar/Emirates/Etihad never have to do.
You're comparing governments that are trying everything they can to encourage visitors, vs. one that's trying everything they can to prevent it. The airline industry is but one casualty in this.
I've flown my entire U.S. family to Dubai a couple of years ago to meet my other family members from all over the world, rather than just have them coming to visit us - because of the onerous US visa regulations. And we're all English speaking, educated, white. I can't imagine what you'd have to go through if you're Indian or Chinese. I'm willing to bet pretty much every H1B, Greencard holder & Naturalized citizen, at least from non-Latin American countries, has taken a flight or two
out of the U.S. to visit family because they couldn't make it work the other way around.
Most Americans have no idea what it takes for someone from a non-visa waived country to visit the U.S. I look at the new travel ban with the "90 day ban" and I got to laugh - it has NEVER taken me less than 90 days to get a visitor visa for a family member. It took me over 7 months to get my OWN visa.
The paperwork for just a plain visitor visa is already more difficult than buying a house. When was the last time you had to have 6 months of bank statements, paystubs and mortgage payments notarized, plus a letter of intent from your employer for how long they plan to employ you for (which BTW. gives them veto power over your trip), and combined with a criminal background check?
Now compare this to Dubai where most people can get a visa in 24 hours with just a passport photocopy and the ability to pay for the stay.
So yeah, the difference between Emirates and Delta is totally government's doing. But not in the way you think.