Current Experience:

When using express shipping I'm noticing that the shipping charges don't automatically update after clicking the checkbox. This requires the user to click the update cart button to see the reflected price - which is not an ideal user experience.

The Problem:

If you inspect the code you see that the checkbox already has:

onkeypress="return submitEnter(document.getElementById('UPDATE_CART'),event);

This will trigger when the Enter Key is press but will not trigger if the checkbox is clicked - so it appears the programmers forgot to include the onclick attribute.

The Solution:

Add the onclick attribute to the checkbox and have it trigger the same function:

onclick="return submitEnter(document.getElementById('UPDATE_CART'),event);"