Where do private universities (LPU, AMITY or SHARDA) fail compared to IIT or IIM even though they provide all facilities and also claim to have the top foreign faculties?

Having foreign faculties or providing world-class facilities is not the only thing necessary to reach the level of IITs and IIMs. There are several necessary aspects that distinguish such private institutes from elite institutes like IIT and IIM, like - 

• Students at IITs have different levels of educational qualifications.
• Students of IITs and IIMs are confident to reach heights in their work careers. But, this passion is mostly missing in 90% students in of private colleges 
• Regular students at private institutes are satisfied with Rs. 4-5 LPA packages.
• Students from IITs usually have excellent depth in mathematics, and in coding. 
• Students from private colleges make several mistakes in their preparation, which affect their entry into institutes like IITs. But, your hard work in college can surely make you successful.
• Students are even placed in companies like Amazon (Rs. 16 LPA), Adobe (Rs. 8 LPA), Sandisk (Rs. 8.5 LPA), etc.
• There are some institutes like BITS, VIT, Manipal, Dhirubhai Ambani University, etc, that are excellent institutes, having good faculties and enough resources. 
• Other than those, most private institutes in India are not in good condition.

These are some of the main reasons why such private institutes, though providing excellent infrastructure and faculty, fail to reach the levels of IITs and IIMs.