ANSWER: Electronic Communication and Internet.
EXPLANATION: In yesteryears people used to depend on newspapers for news of what has happened in the city, country or worldwide. A news which happened in far away countries may take days to get updated on a regional newspaper. Technological advancement eliminated this wait. Internet news websites now provides news from all the world in just minutes from it happening. This service in today's date is also free and doesn't require anyone to buy any newspaper or anything of that category. People just would need a smartphone with an active Internet connection for the whole facility. The newspaper journalists have been negatively affected by this.
Similarly for postal service, people would wait for days to receive a mail sent from another part of the country. Nowadays, electronic communication has made that easy where people would receive instant message from any part of the world within seconds. This has negatively affected the postal workers.