Is GST really a One nation, One tax system?

Goods and service tax (GST) 

Goods and service tax (GST) has really proved impressive in market. Earlier there were multiple taxes extracted from the people which was really annoying but since the introduction of GST, a single tax have been imposed on the various products thus increasing the transparency in the taxation system giving boost to our economy.
In India GST has primarily been divided into 5 slabs i.e. 0%, 5%, 12%, 18% & 28%.
And the various goods have been categorized into these slabs.
But still. There is an issue related to fuel and alcohol. Why haven't they been bought under GST. It is clearly observable that the prices of fuel are sky rocketing day by day and I guess you might know that there is nearr about (40%-50%) tax implemented on them. There for giving a good boost to economy these products need to be subsumed under GST, then only GST can be termed as one nation & one price.