some background from someone who lives there and followed this from the day it was announced
This was one of the major populist campaign promises they made for the 2011 general elections.
"They" being the populist PT party, effectively run by the exiled convicted felon Thaksin Shinawatra.
Reminder: him and his party got barred, which didn't stop him from getting his brother in law elected as PM, and now his little sister. The latest rumours (vigorously denied) are that his son will enter politics to succeed him, sorry her. Never mind that, they are passing a budget to allow 2 trillion bhat (about 80 billion USD) of borrowing for infrastructure investment to be repaid over 50 years.. Anyone want to guess where 10% to 30% of this money is going to end up?
Other policies they put in place where "first time car buyer tax discount" - put that in the same manifesto as "solving horrendous congestion in Bangkok" for a laugh (TS said he was going to solve this within 6 months when he got elected... 8 years ago now), the "rice price pledging scheme" which basically buys/rewards the loyal north-eastern farmers' vote. (more legal way of buying vote than outright payoffs, though those are also well documented).
Now, corruption is endemic Thailand (and pretty much everywhere in SE Asia except Singapore), and from the onset it was pretty clear that the procurement of the tablet devices (the dodgy bidding process, use of intermediaries, etc), the allocation of the funds for training, etc. that it was going to be just another of these big projects where politicians are guaranteed some new luxury cars and condominiums before anything gets signed. First the tablets were meant for Prathom-1 students (7 year olds) then they decided to change that, ... And now they've cancelled them for the southern regions (those that do not vote for PT).
Another funny thing was when they had delays (backhanders not paid yet?) and had to spend some of the school funds buying the books that the tablets were meant to replace...
Summary: shambolic project designed to win votes and steal funds, not designed to improve education standards. And guess what, the educational standards will remain abysmal.