Costco evening employee here:
Yeah, we check those at closing time. As well as behind the mattresses, the bathrooms and anywhere else someone might reasonably hide. There are generally people stocking stuff for 3-4 hours after the store closes and from 5 hours before the store opens in the morning.
There's a small window when the place is completely empty, but it's only from about midnight to 4am.
As someone who lived during a large chunk of the Cold War, let me add some personal perspective on this. You are absolutely right in that the Soviet Union and the West were in a war from WWII on. A spy war, an economic war and several hot proxy wars.
The US lost nearly all of those, but they did win the economic war, and in doing so broke the USSR economically and politically.
After the USSR fell, the Cold War was over. Done. Finito. To emphasize this, capitalism came pouring into all the former SSR's and former Soviet citizens got to taste consumerism triggering chaos that took a full generation to hammer out. And then the 2010's came along and Russia began using it's natural resources to become more and more integrated with Europe.
To the point where some analysts were beginning to be worried that Russia might come to dominate the EU economically.
In fact, if Putin had waited another 5 years Europe would likely have become so dependant on Russian natural gas that they would literally have been unable to effectively protest any move Russia made, in fear of them turning off the tap. Russia was on the road to being THE dominant power in Europe, and Putin literally threw it ALL away chasing dreams of a renewed Russian Empire.