Many businesses in the UK operate comfortably with revenue less than £90k. Sole traders mainly. But yes, once you employ staff it's likely you'll be looking at needing a higher revenue.
Sole traders working labour only may operate below this comfortably. But this is irrelevant to this thread about international trade in GOODS. Not many who are shipping goods and trying to make a decent income off a margin will fall under £90k. If you think you want to make £50k a year on a 25% margin, for instance, you will smash that threshold.
Fair. I wanted to compare the German and UK thresholds more generally (the German threshold seems very low to me even for labour-only sole traders). But I would agree with you that trade in goods across borders would very likely cross the UK threshold very quickly.