i think the real factor in the different times in different mags or shows really comes down to the track and weather. it's never just gonna be some joe schmo that hops in the car and tries to get the best time on the first try, it's gonna be a professional that tries to get a good time out of multiple attempts.
even a regular person who isnt a professional driver can improve a 0-60 time in a manual car. all they have to do is try bunch of times through trial and error (ie launching from different rpms, clutch-play, throttle-play, etc).
but factors like a 50 degree difference in blacktop temps is uncontrollable and there is really no way to improve upon it. a hot blacktop is gonna get you better 0-60 than a cold one, and colder air is gonna get you better 1/4 mile times than hot air, etc
so basically i think the important thing to question (instead of saying one mag has crappy drivers or whatever) is where they are testing and how the conditions are. normally a show like motorweek will have a little blurb about their track conditions while showing the car sprinting from a stop, but sometimes you don't get the conditions in the mags or online articles.