Hey Phil
Have you heard the saying "You get what you pay for" ? .... That's the answer right there
Like anything manufactured - you can make it as cheap as possible or you can go belts & braces. You can use cheap labor or not
Redarc is a good example (if that is one of the brands you are talking about ) - Local design , development , manufacturing ..... who don't cut corners when it comes to raw materials . That's why they have an excellent reputation for quality products ........ & you pay for it.
I work with local manufactures & I see how companies chop & change to save a buck ..... then you have the ones that design their products using specified raw materials (regardless of the cost) & they dont change them.
Then there is the functionality & features of the product - what tech is used & where it is sourced .
If you have ever seen inside a cheap LiFePO4 battery & compare it to a high end one - you'll see what I mean .
A lot of the products on the market are produced in jobbing shops in China etc ...... You can buy from them & they will stick any branding on it you wish . The quality can vary but they are cheap - eg You can pay less than US$200 each for a LiFePO4 100amp battery .
This applies to solar panels , inverters , chargers etc
It's not a complicated topic & really boils down to buyer beware , you get what you pay for & what your expectations are.
Chris