Honestly the problem with refugees is not allowing the border to be open but in offering benefits and accommodation. Since this is paid for by taxes it is highly open to corruptive uses. It also creates an artificial incentive for people to come. Many of the boatloads of drowned refugees trying to get here might not have done so without these subsidies. Most of the men coming probably want to work and send money back. However when they get to Germany they are disallowed from working and kept in refugee camps where frustration grows which is likely what leads to outbursts of anger.