life is getting busier and busier and convenience is the new crowned king in most developed countries
We were far busier when we worked 60+ hours a week in industry (it wasn't that long ago, and I was one of them), yet we ate fewer takeaways back then, so it's just an excuse in my opinion.
I still work very long shifts (including nights) but I can easily cook three different dishes (equalling up to 18 portions) in a few hours on a day off. This saves time later, as it takes about 5-7 minutes to reheat in a microwave. That's truly fast food :)
It's easy to do if you know how, but "too busy" generally means "no time for Facebook/TV/the pub" etc. these days. A lot of people are just lazier than they used to be.