I was once helping a previous landlord install a new dishwasher and during the first test cycle I opened it and he yelled “NO WHAT ARE YOU DOING”. Turns out he thought they filled up with water like a clothes washer. A window really would have helped him.
A surprising amount of people labor under the assumption that they lock shut somehow and the door can't be opened while the machine is running which is bad in case "something goes wrong."
A) No they don't, and you can easily open the door as you have observed, and
B) If the thing were having some manner of hypothetical catastrophic meltdown, why would you want to open the door as your first impulse anyway?
People also near universally have a serious misconception about how much water a modern dishwasher uses, or rather how much it doesn't. Everyone unanimously insists to me that they can hand-wash the same amount of dishes using less water than a dishwasher. No, you can't. They think it's running water constantly while it's in operation and don't understand that it fills with 1.5-2 gallons of water and recirculates that through each phase of the wash, usually resulting in only two or three fills.