You have absolutely no idea what their constraints are or what their IPv6 decision making process is. Neither do I. It might be operational issues. It might be legacy code. It might just be because they've figured not doing it makes them more money or because they think not enough customers are asking for it. Hell, it could be as simple as the right executive thinking "IPv6 is a fad" and roadblocking. But it's not "because the hardware doesn't support it"; that's a long ago solved problem. And AWS designs/builds their own networking gear, so they aren't waiting on Cisco or whomever to give them what they need...they would have done it years ago.