Rail automation is the ability to control train movements without a driver and GoA 2 is the first level that accomplishes this by introducing the core rail automation functionality.
But the jump from #GoA 1 to GoA 2 is an order of magnitude higher than the jump to any other grade (such as GoA 2 to 3 or GoA 3 to 4) due to the complexity and amount of automation required.
Hence, why is the jump to GoA 2 a difficult jump?