GST bill from swiggy/zomato?

yes they have started adding it and guess what its instead benefitting the restraurants/swiggy.

For example we go to a restraurant and buy a biriyani and they charge lets say ₹200/- inclusives of GST. 

At swiggy GST is added separately on that ₹200 and also generally swiggy prices are comparitively higher than direct.

So it becomes 5% of whatever the price be it ₹250 or whatever.

And now comes the loot , if you get any discount of whatever amount the gst still is on the item price and not the discounted total.

The way swiggy has implemented is simple , to restraurant guys its a benefit that they dont need to fraud and neither they need to reduce their cut ,just passed on to customers directly 

Its from longtime, gst on before discount prices. And most of the restaurants are adding packaging charges.

and packing charges are charged arbitrarily, some restaurants charge rs 50 for rs 250 order 

But for amazon, GST is on discounted price.  How can the company charge GST on discount? 

I see something wrong here. Company might not be paying the complete GST to govt. and fooling customers.