The thinner the phone, the thicker the case I can put on it with the same total thickness. It's incredibly rare to see a case-less phone in the wild these days.
Most light and simple(no suspension) road bicycles weight usually 10 kilos, most mountain bikes do weight 15-20 kgs.
In Holland, most bicycles you see on the street are simple and cheap.
And a 1.5kg bike? What kind of bikes are you looking at?
In general, since we are so flat a country, bike weight doesn't matter much. We'd rather have extra fancy stuff on a bike than have a lighter bike.