If anyone has to be blamed, it has to be the mother. How on earth do you travel internationally and forget a visa? No country allows entry without a visa, so why should India? Blame yourself. Rules are rules - the authorities cant have one set of rules for kids and one for adults.
"I hope bureaucrats at higher levels hear about this incident, so that another 12-year-old doesn't have to go through the same ordeal," -- another 12 yr old wont go through this ordeal if that kid's parents has the sense of checking their documentation before leaving for the country. As far as the sri lankan goes, he must've been on a diplomat visa, plus was a foreign dignitary, and will be treated differently. Diplomatic visas get special treatment anyway. Stop whinging and blame your own negligence. How does someone embark on an international flight and yet not bother to double check their documentation is beyond me...