Keep in mind that the memes you see are extreme examples. The vast majority of compound words consists of 2 or 3 words. Like Ofenreiniger (oven cleaner) or Werkzeugkoffer (tool box). Werkzeug being a compound word itself, made from “Werk” & “Zeug” meaning craft or work & gadget. These extremely long words tend to describe very specific, often niche items and are just rarely used in common language. Most people would call the thing in the picture more generalised “Feuerwehrauto”. Sufficient to describe it for most people, but not as precise as the long compound. It is basically a question how much details you want or need to communicate.
Keep in mind that the memes you see are extreme examples. The vast majority of compound words consists of 2 or 3 words. Like Ofenreiniger (oven cleaner) or Werkzeugkoffer (tool box). Werkzeug being a compound word itself, made from “Werk” & “Zeug” meaning craft or work & gadget. These extremely long words tend to describe very specific, often niche items and are just rarely used in common language. Most people would call the thing in the picture more generalised “Feuerwehrauto”. Sufficient to describe it for most people, but not as precise as the long compound. It is basically a question how much details you want or need to communicate.