Why is only one proton transferred in the reaction between sulfuric acid and sodium chloride
Sodium bisulphate (pKa ~ 2 - https://en.wikipedia.org/wiki/Sulfuric_acid) is a much weaker acid that hydrochloric acid (pKa = ~ -7), which means that chloride is not a strong enough base to deprotonate sodium bisulphate.

However all acid pbased reactions are at equilibrium.  Roughly one part in 10^9 of the species involve sulphate anion, which for all practical purposes is negligible.

Table of pKa charts: http://www.lauher.com/che142/acidbase.pdf