We still use checks on a regular basis and I do keep my checkbook with me.
The schools the kids attend don't do electronic transfers. The only school-related electronic option is to refill their lunch accounts and they charge an extra fee for the convenience so I send in a check. Also daycare and certain small businesses only take cash or check. Most of our bills I pay through online bill pay through the bank but any medical bills get a physical check. We ran into issues awhile back with the hospital issuing bills for the same patient with about 6 different account numbers and then not being able to figure out which account to credit them to.
One doctor we use will not take cards, only cash, check, or money order, which would be.....ok I guess, but he also doesn't participate in any insurance. The pediatrician referred us to this particular doctor and when I called to make the appointment they said yes, the fees for the initial evaluation are $1500 cash or check and our next available appointment is in 8 months. Oh, but this is a serious situation, so we will put you on the cancellation list. Well, you can put us on the cancellation list all you want, we're not going to have $1500 in cash to write a check to you until the tax return comes anyway. I mean we did, we managed to scrape it together from savings and such but still. Now it is $270 a month, cash, each time we go. I swear if the guy wasn't as good as he is I'd tell him to take a hike.
ETA: DD13 is on the middle school ski team. Each October we have to give them a $200 check for a coat deposit which they then proceed to hang on to until the end of the season when we return the coat....in March. Last year the booster officers were chatting about how maybe they would just ask people at the get go if they would like to just donate the $200 to the team and then not worry about hanging on to it to give back. Umm....no thank you, I want my $200 back thank you very much.