I stand corrected Re. the Lulav & Tefillin etc..
However, from where do you get to this whole סברא that because by this particular Halacha the shu"a paskens that beis din is אין כופין, that therefore there is a lesser practical obligation?
Since when is the obligation any less? From where do you deduce that because a beis din is not kofe, makes any difference vis-a-vis practical obligation?
Do you have a source? Or is this plain בּויך סברות?
First of all, halacha doesnt start and end in the shulchan aruch, in order to understand the Shu"a we must look back at his sources all the way through to the torah.
Now, do you really thing the practical obligation to wake up before the neitz, is the same as the obligation to make a bris milah?
Now, Beis din are kofe to be mekayim anything that one is absolutely required to do. This is because it is their responsibility to ensure one complies with all obligations. Therefore, they don't have to wake people up at alois, since that is not an absolute requirement, but are koife people to have a bris milan.
Requirements can have 2 origins - deoriasa and derbanan. In the first, G-D directly commands a specific action, and we know so either because it is written in the torah, or by masoires (Halacha lemoshe msinayi, etc). The second origin is derbanan. Chazal had the power to make commandments similar to Gd. For example, the requirement to take תרומות ומעשרות bezman haze (according to some opinions) is a commandment similar to the din deroisa of תרומות ומעשרותin the olden days.
Anything not falling under the realm of those two origins, is not a chiyuv.