For the last few years, I've been impressed with how many battery-operated products now include batteries. For years, Batteries Not Included was fairly standard on the side of a box. So much so that the term became so popular it was used to brand other things, like a 1987 movie.
Now, arguably, the expression has been replaced by "Some Assembly Required", which can translate into 8 hours of hard labour, a full set of tools and an engineering degree.
But it once was even worse: in the early days of tube radios, many were sold without tubes! And the tubes were more expensive than the rest of the radio.
We've all seen the Instant food Mix where you have to separately buy and add pretty much all of the (expensive) ingredients yourself.
There are also lots of situations where advertised prices do not include things you have to pay, like airline tickets (airport and security fees and fuel surcharges) and cars (destination charge), but I'm thinking here more about essential ingredients that are not included in the box you buy.
What other examples come to your mind?