Vaccines aren't free but aren't expensive to produce. If people are just walking in off the street to be vaccinated, with no planning, then it is probably past the point where 3% wastage is material.

Waste not want not, a 3% loss isn't great. But this must be one of the fastest rollouts of a vaccine in human history - it just doesn't matter that much. The 97% that is not wasted is the important part.