Yes, and to many on here, "they were"...and the company benefited from that. Make sense?
It would also benefit the company to cut corners, do as much as they can but not stop the rollout for more, which would take years to be "proven" beyond some threshold as safe.
Much of this proof would require long term testing, impossible to do up front so they would benefit from just releasing them anyways.
>what prevents them
Perhaps there is some optimal range, within which they benefit from best-effort (in a given period of time) attempt at producing what they think does something, what they think doesn't do bad things, and then releasing in full volume to cash in. Everything I'm saying doesn't require them to be nefarious either, even just a little negligence can result in "not actually safe".
If they have cover from government, media, and a willing populace ready to assume safety and efficacy, then what do they have to lose?
The world does not work that way unfortunately.
>what prevents them from outright submitting a dummy saline shot for testing instead
Perfectly possibly.
If we assume manufacturers are intentionally malicious, what prevents them from outright submitting a dummy saline shot for testing instead of the real thing, guaranteeing absolutely zero side-effects?