the USA, the most litigious society in the world, does NOT have subjudicy laws governing what can be published before and during a trial without some sort of sanction against the publisher?
That is correct, we have no such laws. The prosecutor in a criminal trial can be disciplined for making certain out-of-court statements, but I gather the absence of such laws in the US comes as a surprise. Yes, we have a cable TV channel called Court TV, which does nothing other than to report on court proceedings, and some of our courtrooms allow live television broadcasts of the proceedings.
If so, how do media groups get away without constantly being sued for Libel when they jump the gun and print something that turns out to be false?
Because if I report, "Mr. X was arrested last night for crime Y. He has been released on probation and is scheduled for trial next month. Witnesses claim they saw him do A, B, and C." then I am reporting facts. There is a difference between saying he did Y and saying, "Joe Blow, who lives across the street, claims that Mr. X did Y all of the time."
"In other news, Mr. Z, the alleged bank robber, went on trial today. Prosecutors introduced evidence which they say shows that Mr. Z's fingerprints were found on the bank vault." That's all strictly factual, and does not take a position on the truth of anyone's allegations.
how do people manage to get a trial without a tainted jury pool?
It depends on the circumstances. You know, the idea of a "tainted" jury is a relatively new one. There was a time when it was believed that having jury members familiar with the witnesses and the parties was a good thing, since they already knew some of the facts. However, jurors are initially interviewed on what, if anything, they know. I was pulled for jury duty last year in a case involving medical testimony. One of the witnesses was a doctor who had treated me in the past, and I still wasn't able to get off of the dang jury.
I should mention that the US Constitution guarantees "In all criminal prosecutions, the accused shall enjoy the right to a speedy and
public trial". A judge can bind the parties and participants to certain disclosure orders, but the "public trial" provision of the Sixth Amendment is taken to mean that the press does have the right to report on trials.
As you can see, there is usually a sense of mutual shock when citizens of British Commonwealth countries and citizens of the US find out that there are distinct differences in what their respective countries consider to be the boundaries of free speech.
What folks in the US
do have hammered into their heads from an early age is that a person accused of a crime is presumed innocent at law until proven otherwise, so the mere reportage of crimes and trials doesn't work as much prejudice as one might think. Of course, anyone is entitled to their opinion on a matter as the presumption is binding only on the court and the jury.