I can't address the administrative problem: I do know that it was not uncommon for many officers to feel that , given a rapid-fire gun, all the soldiers would immediately use up their ammunition. You would think that they would also realize this could actually result in a quick victory.... but I don't know all the debates. Except that, once the Germans won battles with them, all arguments against were futile and breech-loaders were quickly or eventually adopted by everyone else.

However, the technology is actually not that simple. True, it was fairly simple early on to make a locked breech mechanism that could contain the force, which is why you do find some breech-loading guns being made fairly early. The Ferguson rifle was even used by some British troops in the American Revolutionary War. However, using a barrel that was now open at both ends, all these early designs had to contend with the high pressure gas ( around 20,000 lbs/sq inch) that was created when the gun went off. Closely-fitted parts could somewhat seal the breech, but then there was a problem of powder fouling easily gunking up the gun. Designs that allowed some venting of the gas ( like the US Hall rifle) could be risky for the soldier to hold and didn't function all that well. But when flint ignition was superseded by percussion, in the 1840's, it became easier to seal off the breech. The 1841 Prussian Dreyse "needle-gun" managed to work reasonably well with rubber seals, and the Prussian military success with this inspired a lot of research in other countries, resulting in the eventual solution of the modern brass cartridge in the 1850's. While it's easy to think of it only as a convenient way to have a self-contained charge for a gun, the brass cartridge case is most important as a very effective seal to prevent gas leaking from the breech.

It's also the case that more complex firearms just had to wait for the economies of scale that came with the industrial revolution and real machine tools. While it was ingenious, the Ferguson rifle took far too much careful fitting for mass production in 18th century armories already doing lots of hand work. Manufacturing breech-loaders was just more complex and expensive than making simpler muskets. It is significant that the first real example of interchangeable parts, jigs and fixtures, etc. that would characterize later arms manufacturing were employed in John Hall's shop making his breech-loading rifles at the Harper's Ferry Armory in the 1830's.

Smith: Harper's Ferry Armory and the New Technology

Fuller: The Breechloader in the Service