That's not at all true. I'd say it's 50/50 on whether or not you have a dynamic IP. It has nothing to do with being "residential or data center". It has everything to do with your ISP. For example with Comcast you'll have a static IP that might not change for a full year, whereas with AT&T you'll be on a DSL line and able to change your IP basically as frequently as you'd like. It's worth noting these aren't "cure-all's". You're not going to magically pass through all these blocks and not have to worry about rates. All of the same rules apply to whatever you're using the proxies for. For instance, if you have an AT&T dynamic IP and you're creating accounts or posting something and you keep changing your IP it's probalby going to come from the same c-block, or the same subnet at the very least. Eventually you'll just burn the entire c-block of IPs, so you would want to use them the same way as any other proxies.
Ok, I did not know that. Though in my country and I think most European countries it is well over 90% dynamic IPs as well as ADSL that is used. These newer connections over TV-cable, fiber etc are quite rare here. It is very monopolized market.
Regards