Why is glycine hydrochloride more acidic than chloroacetic acid?
Glycine hydrochloride is the amino acid glycine adsorving a molecule of Hydrochloric acid, wich is a strong acid. I think this is the main reason of the acidicity difference, since the pKa's are similar (comparing glycine and chloroacetic acid).

Update: glycine is amphoteric: it can either act as a base or an acid.
In water the hydrochloric acid molecule of the glycine hydrochloride will dissociate: $$\ce{H2O +HCl -&gt; H3O+ +Cl-}$$
Then:
$$\ce{Gly +H+ -&gt; GlyH+}$$
$$\ce{GlyH+ +Cl- &lt;-&gt; Gly + H+ + Cl-}$$
You can conclude, therefore, that Glycine hydrochloride is more acid than glycine (and also the chloroacetic acid). Hope it helps, and sorry for the english mistakes!