To give credit to the Pakistanis,
Their motorway is world class built by Sharif, and Islamabad is probably the most well planned and maintained city in the Subcontinent. Any Indian visiting Islamabad, is invariably surprised to see Islamabad, and disappointed to see Karachi and Lahore.
And Pakistan is geographically a lot smaller (Balochistan is deserted and makes up half of Pakistan). It would be a lot cheaper, and easier for them to start Bullet Trains. And they have only a few big cities that need connecting like Lahore, Karachi and maybe Peshawar.