Here's why:

* Copper is less reactive than hydrogen. In the reactivity series of metals, copper sits below hydrogen. This means copper cannot displace hydrogen from its compound.

* HCl is a weak oxidizing agent. It doesn't have the oxidizing power needed to react with copper.

However, there are some exceptions:

* Concentrated nitric acid (HNO₃) reacts with copper. This is because nitric acid is a strong oxidizing agent and can oxidize copper to form copper(II) ions.

* In the presence of oxygen, copper can react with HCl. This reaction is much slower than with nitric acid and requires heat.

To summarize:

* HCl alone will not react with heated copper.

* Nitric acid can react with copper.

* Copper can react with HCl in the presence of oxygen, but this reaction is slow.