Some older fabrics (15 to 20 years old) are also narrower - this includes some of the "better" brands such as Kaufman and Hoffman.
So - it isn't just the "new" fabrics that are narrower - some of the older ones are, too.
I had also "assumed" that the "newer" cotton wovens - as in 1950 and on - were 45 inches wide. NOT SO!!! Even back then!!
So - yes, it does seem that some of the fabrics are narrower - and some are - but this is not necessarily a "new" thing.
I now try to check the end of the bolt for width - if it isn't shown - or covered up with a price tag - one can ask to have the width measured.
Some fabrics shrink a lot (I've had fabrics shrink up to 2.5 inches in width) and some don't shrink at all. I can't tell ahead of time what a fabric will do.
I'm one of those that prefer to soak fabrics in hot water (gasp!!!!) and then wash them in cold or tepid water before cutting them.
There are also many sewers that skip the washing step.