In heads and tails why is is mostly tails?

Is it?
Let's say you flip a coin three times, and it comes up tails each time. You may state that from your experience, tails is preferred overwhelmingly.
But three tails is likely to occur approximately 12% of the time, and three heads also will occur 12% of the time.
So, instead of asking why coin flips are biased to the tails, perhaps it is better to ask what evidence exists showing that one side is more likely to occur than another. I couldn't find any. I attach the link on coin flips.

In other words you will never know unless of course you count the seconds its in the air and look what side it lands on. That always works.