Someone on a forum (I do not recall if this one or not) commented that in Europe a rack has to have a rating that exceeds a certain weight rating to be used for child seats. And Tubus downgraded their ratings because they did not want kiddie seats to be used on their racks. My Tubus Logo is rated at 40kg, but is now rated at 26 kg. My Racktime Addit is rated at 30 kg, but is now rated at 25 kg.
https://www.tubus.com/en/products/re...oduct/logo-evo
https://www.racktime.com/en/racktime...-product/addit
Also, some companies let the marketing departments assign things like weight ratings.
I have had good luck with some of the Toppeak products that I have bought, but I have not used any of their racks.
Thorn in the UK rates one of their racks at 40 kg, but raises that rating to 60 kg if M6 bolts are used in the mounts instead of M5 which is the norm. So, in the upper ranges of ratings, the bolts may be the limiting factor. I have two Thorn bikes, one uses M5 bolts, the other bike is more heavy duty and that bike uses M6 bolts.
I agree with LeeG, there is more to a rack than a weight rating.
For touring, I want the lower rails to drop the panniers to a lower level, I also want a narrow platform for touring. But for riding around near home, I like a wider platform. Thus, my touring racks are only installed on the bikes for touring and removed after that. While price is important, that is the least important thing I look at when buying a rack for touring.