Aldi in Ireland (and I'm assuming the rest of Europe too) has a new system in place. If sensors above the checkouts detect the lines are too long an automated voice will announce "Checkout 2 will open soon, please start unloading your goods on to the belt". 30 seconds later another announcement will say "Operator to checkout 2 please" so the operator arrives to a checkout with a fully loaded belt.

And the reverse happens as well, when the line reduces another announcement will state that the checkout is closing and customers should not approach that checkout.

I'm always amazed at the little things Aldi does to make their process even more efficient.