I never ever heard or encounter, "no testing" when buying any electrical product before.

its a standard practice in any shop.
but, you gotta buy and pay it first, only then , they will open it there and test it for you before you leave the shop.
why not before you pay? this is because, open-seal-box cannot be sell. the value will drop.
later after opened people say they don't want to buy it.. if 100 people do that, bankrupt.

for a launch product, where there is a long queue.. usually, you cant test it.
cause its gonna take a hella long time for everyone in the queue.. its gonna cost a riot.

for things that you don't buy in the shop, but ask them to send by courier,
is a totally different story, unless you let the shop to open the box (break the seal) and test it for you before sending.
most people want to do the un-boxing themselves.

.