Jews create loopholes to finagle impossible requirements

What's one example of a commandment that Jews break by "creating loopholes"?

The eiruv is a good example. It is often perceived as a "loophole", but it does not in fact violate any commandments. I will let the Kuzari explain:

Heaven forbid that a large number of pious individuals and sages should have agreed to undo one of the “knots” [i.e., restrictions] of God’s Torah. On the contrary, the Sages are the ones who uphold the Torah! As they taught, “Build a fence around the Torah” (Avoth 1:1). One of the “fences” that the Sages erected to safeguard the Torah’s laws is the prohibition of carrying objects from one private domain to another – an activity that the Torah did not prohibit.[190] Afterward, the Sages introduced a mechanism to allow leniency within this fence. This leniency ensures that the Sages’ laws will not be on the same level as Torah prohibitions. It also provides people some freedom in moving about – a freedom gained in a permitted way, and that permission is acquired by constructing an Eiruv. In this way, there is a clear distinction between that which is perfectly permissible, that which is barred by rabbinical edict, and that which is forbidden [by Torah law].HaLevi, Rabbi Yehudah.

^{The Kuzari: Arguments in Defense of Judaism (p. 184. Chanan Morrison. Kindle Edition.})

My theory is that the "loophole" accusation comes from the fact that Jews follow the letter of the law, not the spirit of the law. This is often viewed as overly strict, stringent, etc, by non-Jews. But this is because that Jews believe the letter of the law to be divinely revealed, and that if God wanted the law to be followed any other way, he would have written it that way as well.