Here in Gemrany I there are signs with "voluntarily 30" or similar combined with some surrounding images etc. and yes one can fake it, but most fakes can be ide

Here in Gemrany I there are signs with "voluntarily 30" or similar combined with some surrounding images etc. and yes one can fake it, but most fakes can be identified realtively easily by humans (positioning, color, material (non-reflecting cardboard), ...) some high quality fake sign might however exist for a while. Also there is the reverse: people stealing signs (https://news.ycombinator.com/item?id=25223633 https://news.ycombinator.com/item?id=25223633) or putting stickers on them (or snow, mud, ...) where most humans know what to expect (stop sign, yield, ... have specific shape for a purpose; empty frame where city starts; ...) Going out of a somewhat controlled small area in SV/SFO or AZ is a huge task. Going to a different country requires complete re-learning of the models ... and then there are humans ...