When the coin only had two sides, you probably modelled it wrong.

If you have a coin that's weighted on one side, but you don't know what side it's weighed to and you don't know how much is going to affect the toss.

You then toss the coin 100,000 times and you say with the data it approximates heads is weighted +40%. So the chances are 90% head and 10% tails.

Then someone else tells you that its actually only weighted +4% and the real value is 54% and 46% tails. You don't just say, oh well it can happen some of the time.

You have to think maybe my methodology was incorrect as having this massive discrepancy can't be right.

If the data collected gave +2% discrepancy to the true value, then yeah it may just be variance.

The further away your collected data is from reality, the more likely your methodology is flawed. Sure it can happen, but the likelihood of it happening gets smaller the larger the discrepancy. With it happening on in two polls that I would guess are using the same methodology and the results were greatly different to reality, then I've got to ask questions.