This is all wild to me, alarms not required in a building that is largely unoccupied?! Who cares that its purpose is to fight fires? Especially if people aren’t there often it needs an alarm!

Explain such a logical and self explanatory idea to the lawmakers and bureaucrats of 16 different states. If you’re from the US, you will have a quite good understanding of the downsides of federalism yourself.

Typically, automatic alarms are only required in buildings that pose a very significant danger in case of an undetected fire, unfortunately that does not include the indirect danger of not having a fire station anymore after it burns down.

And most of your firefighters are volunteers?

Yes, a legal requirement for having a professional fire department only exists in cities over a certain size. (thanks to federalism and German history, this is a bit location dependent, in the Western states, the magic number is 100000 inhabitants, in the Eastern ones, it’s 50000) Those cities will have a volunteer fire department in addition to the professionals, the way the volunteers are used depends a bit on the city, some will use them as back-up for large incidents, others will use them for specialist roles, while again others will use them for regular coverage outside of normal working hours. (Or any thinkable combination of that) Larger stations in cities under that size limit typically employ a few paid maintenance technicians who will also respond to incidents. (on their own for small things, in combination with the volunteers for larger ones)

Does Germany not need as many firefighters because many buildings are constructed of materials less susceptible to burning?

Germany does have roundabout 1.1 million firefighters in total, the density is pretty high. This is due to the legal requirements of meeting pretty strict response times pretty much in any village, town, and city. The exact times vary a bit from state to state (again our old friend federalism), and some even make a distinction between urban and rural areas, but typically it’s something between 10 and 15 minutes from an emergency being called in (the clock starts ticking the second you dial the emergency number) to the first unit arriving in sufficient strength to do something about it. The measure for sufficient strength, unless there are other dangers, is a “critical dwelling fire” meaning a fire in an inhabited building with person(s) trapped. The absolute minimum to even start dealing with that according to German tactical standards is 6 firefighters. Response time limits for subsequent reinforcements arriving also exist, and requirements for the total strength and equipment of fire department, depending on the hazards present at the municipality in question.

In order to meet that requirement, the preferred way for municipalities smaller than those that require a professional fire department, is having volunteer fire departments, but in case not enough volunteers can be found, they are legally required to conscript able residents for compulsory fire service.

The “This won’t ever happen to me” vibe is very strong in Germany. We even have a fire service related joke term for it. Let me introduce you to the “St. Florians-Prinzip”, the “principle of St. Florian”, which is centered on the idea of praying to St. Florian, the patron saint of firefighters, to spare your own house, but light someone else’s on fire instead:

Oh heiliger Sakt Florian,

verschon unser Haus,

zünd’ and’re an.

(This principle is also often used to describe NIMBYism)