I take my 18-month old to daycare each morning, before parking my car a few streets away and catching the train into work. It is terrifying to think that one day I might just forget to drop him off.
My partner usually picks him up in the evening. About 6 months ago she was busy so I did it. I picked him up, drove home, parked the car in the garage and walked straight into the house. Something felt wrong, but it was maybe 30 seconds until I realised I'd left him in the car. He was completely fine, but it put the fear of God into me.
Anyway, I'll contribute my poorly thought out technical solution - a thermal camera that monitors the seats for warm bodies, if you lock the car when present it beeps the horn.
Some parents take their shoe off and put it near the child seat and put it back on when you drop the child off. If you forget to drop the kid off you will realize it when you notice you are wearing only one shoe. There are also apps that you can use to log a drop off so your spouse can see and verify.
Putting a air tag or other tracker on the child with a time based geofence is also pretty effective. It should alarm if the child is not at day care when they should be and alarm if the child is near work since you normally don't bring children to work.
There are enormous pressures on a new parent -- stress about getting back to a normal work routine and lack of sleep compound into a unique kind of stress and things start to slip.
For me: I decided I could just slow down a bit. Standing out isn't worth the stress. I don't want to slack, but I don't feel compelled to cram productivity into every moment.
My partner usually picks him up in the evening. About 6 months ago she was busy so I did it. I picked him up, drove home, parked the car in the garage and walked straight into the house. Something felt wrong, but it was maybe 30 seconds until I realised I'd left him in the car. He was completely fine, but it put the fear of God into me.
Anyway, I'll contribute my poorly thought out technical solution - a thermal camera that monitors the seats for warm bodies, if you lock the car when present it beeps the horn.