The text of Hatatarat Nedarim starts like this:
שִׁמְעוּ נָא רַבּותַי דַּיָּנִים מֻמְחִים
"Please hear, expert Dayanim (court)
It's not just that usually we gather three random people to be Dayanim, who are not necessarily "Experts". We know (Tur YO"D p228) that:
מי שנדר ...ילך אצל חכם מומחה..., ואם אין יחיד מומחה ילך אצל ג' הדיוטות ... והאידנא אין מומחה שיהא ראוי להתיר ביחיד בפחות מג
One who had taken a vow... will go to an expert sage... and if there is no expert will go at three simple people...and nowadays, we have no experts, that are worthy to cancel a vow alone, with less the three people.
So, if you need three people, they are obviously not "experts", why do we say they are?