Why did the Ottoman Turks, unlike the Arabs of the 7th-8th centuries, not strive to convert all their subjects to Islam?

The non-believers (they were called raya, i.e. the herd) paid the Ottomans a much higher tax than the Muslim subjects.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.