The problem here is quite similar to the issue of marriage for all. Technically there is (probably) a majority for it but the CDU which is currently in governme

The problem here is quite similar to the issue of marriage for all. Technically there is (probably) a majority for it but the CDU which is currently in government is against it. Additionally there are other issues that are considered more important either because they're more popular or affect more people, so the SPD isn't willing to burn political capital. Given the current political situation in Germany and more broadly in Europe, there won't be any policy change in this legislative period or the next, so at least ~5 years. In fact there is a risk the situation might get worse in the next legislative period. Hard to predict what will happen beyond that, a lot can happen in that timeframe, Merkel will probably retire and the political landscape could shift drastically in response.