What is 'equal protection' under the Constitution?

The SCOTUS made much of the fact that different recounters might treat partially/incorrectly marked ballots differently, using that as the basis for disallowing the recounts that were under way at the time they issued their stay – which incidentally effectively ran out the time available for recount udner any standard. Using that principle, couldn’t some well-heeled disgruntled Democrat, like that Douglas fellow from Palm Beach County, file lawsuits to have virtually every election result in the country thrown out as unconstitutional?

Seems to me that unless every ballot is counted in exactly the same way, the equal protection clause of the Constitution comes into play. This would mean that voting under the following situtations w(sh)ould be disallowed:

(1) different ballot types – how can counting an ‘X’ be the same as counting a punched hole or an electronic mark or …
(2) same ballots, different counting machines – all machines eventually get out of alignment, so even ‘identical’ machines may not register in exactly the same way
(3) single counting machine not recalibrated after each ballot is counted – as all machines eventually get out of alignment

That was not the reason the USSC issued its stay, altho it was the rationale for some of the justices to deny relief. The stay was issued because there was a substanital liklihood that the plaintiffs would suffer irreparable harm; viz., according to Justice Scalia, degeneration of the ballots due to handling.

Equal protection would not require identical protection. Just so there was some uniform standard adopted to judge whether the vote was cast or not. Two of the justices did not even think that that was required and two more were not sure.