does the knowledge acquired in school really applicable in labour market ?

Yes it does, but you might not really be doing all that you learnt in school. The fact is that the knowledge you gained in school help prepares you for so many challenges you might face on a daily basis. The knowledge makes us complete in terms of resoning and way of life.
As for me, i read chemical engineering and noiw working in a Facilities management Company. The fact i have to learn new things on a aily basis.
Note that the knowledge we aquire in school counts a lot.