In the placement process, it is not always the B-Schools that are responsible for reporting inflated packages, but rather the companies. The figure reported by placement cells is referred to as the "Cost to Company" (CTC) and not the take-home salary. This means that simply dividing the CTC by 12 is not an accurate reflection of what you will receive in your bank account each month.
CTC consists of two main components: fixed and variable. The fixed component includes your basic salary, HRA, TA, LTA, employer's contribution to the provident fund, joining bonus, retention bonuses, and ESOPs. The variable component is based on both your performance and the company's performance and is paid out in lump sums either yearly or half-yearly.
Your take-home salary at the end of each month is calculated as basic salary + HRA + TA + other allowances - provident fund deduction - tax. The remaining amount is given to you at the end of the year. To illustrate how companies may inflate their CTC figures, here are a few examples:
Fixed component: 9 lakhs
Year 1 end retention bonus: 2 lakhs
Year 2 end retention bonus: 1.5 lakhs
ESOP: 5 lakhs to be paid over 3 years
Performance bonus: separate/not reported CTC: 17.5 lakhs
Take-home salary: 65-70k
Fixed component + Variable component: 14.5 lakhs
Relocation: 2,00,000 INR (one-time payment)
Supplemental Salary: 3,50,000 INR (supplemental salary is an accrued bonus paid out in monthly installments pro-rated from the date of joining, only applicable during the first year of joining)
CTC: 20 lakhs
Take-home salary: 95-98k
Fixed component: 9 lakhs
Variable component: 10-20% of a fixed component
CTC: 10.8 lakhs
Take-home salary: 65-68k
As seen from the examples, despite Amazon having a CTC that is double that of RBS IDC, their take-home salary is the same. This is the typical way it works. The placement teams likely do not have much control over the process.