You'd think any dual-voltage unit would be able to transition between its voltages.
I agree.
I think as time goes on, things should be improved and tweaked (just as things generally are). Of course, some companies prefer to save money and just regurgitate the same things until they invariably end up left behind and made obsolete.
You could argue that, yes, people survived without screens on trains or automated announcements. They survived too without power points, or Wi-Fi*. LED lighting? Why bother if ordinary fluorescent tubes and halogen spot lights work fine?
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* Trains with Wi-Fi should really be seeking to get upgraded to offer 5GHz (802.11n and 802.11ac) access, which has many advantages. I think I scanned on the GWR HSTs I used last Saturday and I think they were 2.4GHz only. If so, that's a bit backwards.
2.4GHz may travel further, but there are a range of congestion and capacity issues. Many new hotspots are dual mode, and can cope with more users far more effectively. I'd say that most tablets and smartphones made and sold in the last two years are going to be dual-mode (bar the very cheapest models). Laptops probably for even longer.