The paycheques of staff at these firms come from following process. The big perk they offer competent employees is to get a US or EU work visa and be deputed on-site (that is easily a 10X salary hike for people with less than 10 years of experience), and that perk is how they keep salaries low.

You could get more competent people, but they are less likely to follow process (which violates contract terms), and would cost more.

Edit: Also, if you work in one of the big service firms for a US client, you will have to do your day job, and then return to the office later at night to have meetings on US time.