This is the result of significant advancements in machining tolerance (at production volumes we are talking about with cars), improved elastomers, QC, and ultimately engineering.
I just replaced the original oil pan gasket in a 1993 Ford 351W. It was a simple cork seal, impregnated with some rubber elements. Frankly pretty simple.
Back in went a fully elastomeric injection molded part. I guarantee you this seal went through extensive design/FEA to optimize the seal bump to achieve excellent sealability and improved contact pressure and the contact pressure profile over the machined seal face.
Now combine that with better tolerance control and QC on a modern block and you get no leaks.