I broadly agree with V Harikrishnan.
However, the matter must be viewed in historical perspective to come to a rational conclusion.
Eligibility for full wage was reduced to 48 hours of work per week by ILO Convention No. 1 of 1919 and consequent amendment to Indian Factories Act, 1911 effective from 14-07-1921. Before ILO adopted its first Convention in 1919 industrial workers toiled for several hours per day on all days and were paid wage per week. Wage is related to work; weekly holiday became one of the fundamental rights of workers. Therefore to be fair, monthly salary must be divided by the number of working days, i.e. by 26 in establishments following 6 working days per week.
India ratified on 14-07-1921 ILO Convention No1 of 1919 concerning Hours of Work (Industry) which limited working hours to 48 hours per week. Further, India ratified on 11-05-1923 ILO Convention No.14 concerning Weekly Rest (Industry), which entitled workers to enjoy a weekly holiday.
To give effect to these ILO Conventions, Indian Factories Act, 1911 which was then in force was amended vide notification dated 14-07-1921 and 11-05-1923. As per Section 22 of that amended Act no person shall be employed in any factory on a Sunday, unless: (a) he has had, or will have, a holiday for a whole day on one of the three days immediately preceding or succeeding the Sunday, and (b) the manager of the factory has previous to the Sunday or the substituted day, whichever is earlier, given notice to the inspector of his intention so to employ the said person and of the day which is to be substituted, and has at the same time affixed a notice to the same effect in the place mentioned in Section 36.
It is obvious that Factories 1948 Act substantially continued the provision as contained in Indian Factories Act, 1911.
There was no need either during 1923 or 1948 to expressly state that wages should paid for weekly holiday because full wage used to paid for the whole week including Sunday, which was a working day until ILO Convention declared it as weekly holiday and consequent amendment to Indian Factories Act, 1911 effective from 11-05-1923.
It is significant that ILO convention No.14 concerning Weekly Rest (Industry) is applicable to industrial undertakings such as mines, quarries, manufacturing construction, transport etc. Those employed in commercial offices including trading establishments, theatre etc., remained out of coverage of the Convention No. 14 of 1921. Therefore, a separate Convention was adopted by ILO in 1957 vide Convention No 106 concerning Weekly Rest in Commercial Offices to confer the right to weekly rest to these employees. Generally, the employment practice in this latter category of establishments was in the nature of monthly employment on salary. These workers normally enjoyed relatively less working hours compared to industrial workers. This employment practice probably led ILO to stipulate in convention No 106 of 1957, vide Article 9 that “there shall be no reduction of income of persons covered by this Convention as a result of the application of measures taken in accordance with the Convention”. Later day enactments as for example in Shops and Establishment Acts of various State Governments therefore specifically lays down that weekly rest must be allowed with wage.
In several advanced industrial countries labour law reforms reduced working hours to 35 hours per week; and five working days per week. In India the Government and employers consider that progressive legislation of British regime stand in the way of ease of doing business in India! If one adopts this new perspective such a rationale would tend to pay as much less for workers so as to enhance the ease of doing business. The question is would that approach be fair?