If they join a religion that isn't on the state approved list, they can't get married there and hard or extra expensive to get buried. There are some limits on religious freedom.
That’s a lie. You can form a civil union, which is very similar to the religious marriage. On the other hand, does Hamas recognise a Jewish marriage?
They can just get married abroad. There are even online ceremonies now.
A decent number of Israeli Jews have to do that as well, since Israel recognizes Jewish marriages only under orthodox rabbis. Some Israeli Jews are not even considered Jews under strict orthodox rules.