You might have been lured in by a very bad TEDx talk (http://www.ted.com/talks/johanna_blakley_lessons_from_fashion_s_free_culture) but this is pretty much entirely false.
Mathematics is not profitable, by pretty much any metric imaginable. Lots of things that use mathematics are very profitable (pretty much the entire IT sector and any heavily engineered business), but mathematics itself isn't. In order to translate mathematics into goods and services, a significant amount of work is required, and whilst the mathematics itself can't be protected under IP laws, the product of the work put into making the service or good can. Programs can be copyrighted, goods or services that leverage mathematical properties can be patented if they meet the required criteria, and so forth.
The automotive industry is a hot-bed of IP protection. Ford alone has been assigned over 6 000 patents in the US, looking only at the records from 1979 onwards (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=0&f=S&l=50&d=PTXT&RS=AN%2FFord&Refine=Refine+Search&Refine=Refine+Search&Query=AN%2FFord+and+Global+and+Technologies). Toyota, VW and all the other major automobile manufacturers have similarly huge patent stashes that they guard preciously. In the past decades they have been more aggressive with design patents in order to stop aftermarket parts makers from successfully entering the replacement parts market. Design patents are ubiquitous, and pretty much every single car since the 70s has a few... Porsche (http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN/D673484), Toyota(http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN/D688160), Ford (http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN/D488405) just to name one in each major market.
As for fashion, well it's hardly a brilliant example of a "beneficiary" industry when it is the sector that pursues the most aggressive out-sourcing and mechanisation strategies. Buying things made in the USA isn't always easy, but for clothes it's almost impossible. A few companies that are pushing the high end of the market manage it, but that's hardly a ringing endorsement of a sector that is in great health.
But beyond the obvious financial difficulties that many fashion companies have had over the past decade or two, a more potent criticism is the actual lack of innovation that fashion has brought over the past century or even two. In 1930 IT didn't even exist as a sector, and pretty much every aspect of our lives have been transformed. Cooking has seen the meteoric rise of the microwave oven and the freezer, whilst fridges became basic home appliances. Communications went from the radio to TV and online broadcasting, whilst telephones have become mobile personal assistants. Cars have seen vast transformations in performance, variety and ease of use. Air travel has gone from a luxury reserved to a prestigious and wealthy elite to a popular mode of transport. Electricity has definitively finished its transformation from a convenient novelty to a base necessity of achieving any decent standard of living. Plastics have gone from being synonymous with bakelite to a whole group of materials with ever more varied properties...
The changes in pretty much every facet of life have been huge thanks to sustained innovation over the past century. What has fashion (or even apparel in a larger sense) brought to the table? Very little I fear. New materials have been brought to the market by companies that had nothing to do with fashion, being only used by fashion as a direct substitute for a different material well after the product had been developed (like Nylon, developed by DuPont and first used as toothbrush bristles and only used as a direct replacement for silk in stockings seven years later... by DuPont ! ). Sure, some fashions have done away with some conventions (hats), or shifted perceptions on what is appropriate or not (jeans). However nobody can hold a straight face whilst claiming that the fashion industry's lack of IP regulation has spurred it to greater innovation than heavily protected sectors such as IT or manufacturing.
Going back to the initial statement for a second, it still seems surprising that all sources seem to agree that people spend less each year on clothing (and fashion in general) than they do on cars by a vast margin. Whilst the latter are certainly extremely useful and in rural environments almost mandatory, the former is quite literally mandatory in order to live in society. That a non-necessary sector manages to trump so convincingly a necessity of social life shows that for many people fashion fails to capture their imagination and interest, whilst the automotive industry manages to do so and in this manner convince them to part with a greater share of their money.