Space X has already proven that their designs work.
ULA has yet to begin a ‘recoverable’ first stage test.
Bezos is a monopolist, and cannot be anything else in any endeavor of his.
The engines of the Space X BFR are just more of what already works. Simple. Easy.
Of course, NASA is whining about getting back into the business, after an 8 year or more hiatus. Which to me means that they have to be designing for a while longer, while Space X marches on.
Any previous effort to catch rocket engines with a helicopter, such as ULA Vulcan operation proposes?