Gotta note that the first part “the number of armourers in the Czech towns was much higher then in German towns” is wrong! (Not completely but partially)
If we talk about armourers who made armour (plate, maille) it 's definitely wrong! (For weapons smith --> I 've got no idea, I’m not interested in weapons)
(Talking about armourers that made armour now)
The number of armouring workshops outside of northern Italy around 1400 was quite low. Bigger cities had armourers, this is true but looking at them in detail you will notice that many of the workshops were run by one single person. The bigger workshops, at 1400, were still in northern Italy, about 70% of the armour for Europe was produced there. 20% go to south Germany and the final 10% is the whole rest of Europe. This keeps until 1500, afterwards the numbers change, Germany gets more influence on the market, Italy produces less and new workshops rise. But still armourers, concerning guys that make armour, in Prague did surely not outnumber the german ones.