Journalists do not normally work like that. That might be how beefs are fought on social media, but of course screenshots are easy to fake anyway.
That is correct, but it's not to media's credit. Most journalists say basically, "Trust me, I'm the authority, I wouldn't be allowed to say this if it were simply lies. I could prove it to you but I won't, at worst I'll be forced to prove it to my peers. (And you aren't one, peasant)." They practically never link to the scientific paper they just reported on, certainly not to anything that could let us check politically controversial claims ourselves.
And how could it be otherwise? You aren't the customer. Ads, or worse, billionaire political patronage, is what pays the bills for media companies. Their authority - the blind trust people have in them - is what makes them valuable for their actual customers. They're not doing science, the last thing they want is to make it easy to check their work (although, maybe I'm too charitable to scientists too here, if they make it easier to check their work it's often the bare minimum, but I digress).
One of the original points of WikiLeaks was to make a kind of journalism where claims were easy to check from the sources. But you can see how controversial that was.
I don't understand what your point is.
What is the reader assumed to do about an article that does not bring any proof?
The video of the missile exploding is also easy to fake, but it's an important element behind the reporting.