The thing with DDR3 RAM is as I understand it not really an "also". It's not that they are made differently it's just that the demand for "the best" RAM is so high that all production is going there. The DDR3 market isn't just as willing to pay such a markup.
Makes sense. I have a few old servers I still have running as CI runners, recently dished out more for 32gb of DDR3 than I did for equivalent DDR4 back in 2021. :(