Banning the Burka is well and good, but it's become the European equivalent of banning flag burning. It's a narrow approach to a much bigger problem that exists mainly as a source of political theater. And which politicians often have no intent to carry out or expect the courts to block for them.
Notably, Merkel is emphasizing her policy as one of those "whenever legally possible" deals which all but telegraphs that she isn't serious about it. Not that it would come as a surprise.
Despite her near Stalinesque numbers, much of Merkel's party is running scared and proposing tougher measures. Germany is a very different place, culturally, than the UK or the US. Merkel's endless time on the throne alone testifies to that. But Merkel's migrant disaster was much bigger and took effect much faster. The political consequences of that may only be coming.