[Grammar] The polls show/showed

[kadioguy]

The polls show Labour leading with only 10 days left until the election.

https://www.macmillandictionary.com/dictionary/british/lead_1

The polls showed Obama leading Romney by 3 percent.

https://www.ldoceonline.com/dictionary/lead

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Why is the first "show" while the second "showed"?

Friend A told me, "To me, it's ‘show’ if you're talking about the polls relative to the time of writing/present; ‘showed’ if you're talking about it as if you saw it in the past and are now writing about it. But this difference really doesn't matter, so you'd probable be safe with just brushing it off as a stylistic preference."

Friend B said, "I would use ‘show’. That might just be personal preference. It's how everyone in the south of England would say it. ‘Show’ and 'showed' are interchangeable to me."

I agree with them. However, I would also like to hear your opinions.

 

[5jj]

it's ‘show’ if you're talking about the polls relative to the time of writing/present; ‘showed’ if you're talking about it as if you saw it in the past and are now writing about it.

That's fair enough.

It's the way the unmarked (present simple) and marked (past simple) tenses are often used of situations in present/general or past time.