Competition
Article here.
Arianespace is betting on solids, while SpaceX is going after liquids and eventual full reusability, which will reduce launch costs even further. Currently, SpaceX already underprices Arianespace by about $200 million for a GEO flight.
Arianespace has the advantage of an excellent reliability record, and it will be a while before SpaceX can rest on any laurels in that area. Whether that's worth $200 million a launch depends on the customer.