I disagree. AZs are completely independent data centers kilometres apart. For any businesses which may need low latency but still want full HA (e.g. finance sys

I disagree. AZs are completely independent data centers kilometres apart. For any businesses which may need low latency but still want full HA (e.g. finance systems), it's a blessing. This requirement cannot be fully covered with separate data center regions, something like an airplane crash would still hit everything.