When a tank driver wants a drink, he tends to reach for a beer. You can open a beer bottle with your teeth, but a better way is to crack it open on the ridge of a hard surface. 

As the beer bottles in the inside of the tank were opened and consumed, the hard rim around the dashboard degraded. Eventually, entire units had to be replaced. Now, tank drivers are not supposed to consume beers whilst on duty, especially in Middle Eastern countries (yes, it was.) Therefore, you cannot sell a tank with a bottle opener. But, what you can do is to reinforce the metal rim of the dashboard so that you can reduce maintenance costs (it's called "integrated logistics support".)  Any beer drinker would recognise its potential. 

Tank designers are bound up with specifications on firepower, navigability, manoeuvrability and robustness. But, how many take account of the demands of a parade through the capital city? As an array of thirty tanks advances down the Champs Elysées, each must have its barrel perfectly aligned. Whoever would have thought that a vehicle designed for the heat of combat would have to look so beautiful?