Your first point is correct. Though both PTCL and TW have peering agreements with Google (and similar content providers, e.g. Facebook), the difference in ping is due to the fact that both have different commercial agreements i.e. depending on physical link feasibility and financial (read cheap) reasons, they peer with Google via providers in two different countries. Which brings me to the next point, Oman & UAE use large neutral POPs and are major data hubs that peer with other Internet Exchanges all over the world due to their sheer amount of investment and submarine capacity. And since I've seen people mentioning India quite a few times here's my 2 cents - the situation with India is quite complicated (duh). Even though there's plenty of capacity between the two countries, at this moment in time peering agreements are hard to reach owing to the political situation (and perhaps more importantly for ISPs - network security, which I won't go into). At the moment it's easier and cheaper to rely on other carriers for data transit rather than direct peering.