IMO, the rule should allow for ref's judgment re: "deliberate" and "not deliberate" handballs. Like that handball in Scotland/England was not deliberate, and neither was the one on Sissoko in the CL final last weekend, so (if I had the power) it would rate a free kick from outside the box. Deliberate handballs get PKs.
There would still be argument over what a deliberate handball is, but at least there wouldn't be the incentive for the attacker to kick the ball at an outstretched arm to get a cheap penalty.
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Scotland got that first goal, but now they are continuing to try to play out of the back instead of getting the ball up the field. They took ten minutes to put a ball long and immediately connected. No urgency from them here.