Where Are All The Toilet Seats?

I know they sell them in Mexico, I've seen them in every department store, but where are they?  This has been my biggest pet peeve!  I keep waiting to stumble upon the big secret of where they all are….Public washroom stalls will have missing doors with a seat, or a door but no seat, and some won't have any of the above and be full of s&*$ and plugged up because some foreigner put paper in the toilet.  You must always put toilet paper in the garbage bin, as disgusting at that may be, never flush it down the toilet, plumbing systems here cannot process paper.  

Bathrooms at bus stations will have locked revolving gates that you have to put a 5 peso coin in to get access - these will usually at least have paper, but still no toilet seats.  In airports, bars and malls, there is usually a señora who works at the sink for tips, she will hand you paper, and offer a little basket of gum, breath mints, condoms, etc. for a small fee.  In modern hotels, most likely there will be toilet seats, but not always, if it's a rustic hotel in a small town, not likely.  At the gas stations while travelling on highways, you are on your own baby - no toilet seats, no paper, no water and no soap!  Don't get me wrong, soap and toilet paper are widely available in Mexico, they just don't think it's a priority for bathrooms.  BYO!