Maitree Express: মৈত্রী এক্সপ্রেস - দুই বাংলার সংস্কৃতি ও ভাতৃত্বের মেলবন্ধন - Joydeep Roy

Not every thing is decided by revenue brother...
Gaya is arguably the biggest tourism center Bihar has to offer!
Gaya has an international reach....DBG can never touch GAYA's level so it is out of question...
MFP is not only a bigger station than Darbhanga and but also lies on the BJU-MFP-HJP-SEE which can be considered a semi-trunk route if not a trunk route...
MGS...
more...

is ECR's biggest and most important junction, no Patna isn't, Almost 85 percent of ECR's traffic plies though MGS....also it's closeness to BSB and UP Elections might have played a role....
Like I said not everything is decided by revenue brother...actually revenue generation in most cases plays little role in facilities being provided....political might does!!!