Last time I went to Germany (2015), T-Mobile had run out of physical SIM cards. We queued up at Vodafone for half an hour. By this point, the store was closing. The employee gave us a SIM but didn't activate the plan correctly. So our €10 was all used up with hours instead of being good for a month. And we had to go back in the next day to sort out it.

eSIMs, EU roaming regulations, and carriers like Google Fi have all improved the situation markedly. Though dealing with Vodafone has not.