2. Millions of Jews keep Shabbat. There's no such things as Chassidic Jews are "serious" about it or keep it more. There is something called Halacha (Jewish Law) which dictates exactly how to keep everything including positive actions and negative prohibitions.
3. A Jew cannot have his business open on Shabbat period and that includes benefiting from it. That's why B&H are closed on Shabbat and all the Festivals.
I think the point was that in this day and age, many people who identify as Jewish do not fully observe the Jewish law (for example, by working on Shabbat or not keeping Kosher). Many businesses run by Jews remain open on Saturday, which is precisely why the behavior of closing a large business can create confusion amongst those who haven't been exposed to it.
It's no different from identifying as Christian but not following the literal word of the Bible (find me a single person who actually does verbatim and I will be phenomenally impressed).
It's not that Chassidim are "more serious" but rather that their dedication to observing Jewish law to as great a degree as they can manage is what drives them to identify with that group in the first place. That is to say, cause and effect are reversed here. Chassidim don't follow every word of the Torah, either. Just a much higher percentage than most other Jews do.
At the end of the day religion is a very personal thing, and one of the reasons I love living in America is that you can choose to live however you want, even if that means closing a hugely successful business every Saturday, and people may wonder why but nobody can tell you that it's not okay... that's freedom of religion. Identifying as Jewish even if you never attend synagogue, don't observe Kashrut, and work on Shabbat is also your right. As long as you eat bagels and lox. If you don't do that, then go find some other religion, because Judaism doesn't want you anymore.