- mobile phone and data roaming, the most notable user-facing innovation

- the single market itself with all the associated side legislation (GDPR, VAT OSS) that allows every tiny small business to serve the entire EU

- Schengen free-movement zone

- Euro currency

- SEPA instead of national schemes (ties in into the single market aspect as well) with everything from card payments over wire transfers to direct debit covered. Strong authentication required for opening bank accounts. No more paper cheques. (Directly compare all of this to the hot mess that the US is)

- EPD PS2 that forces banks to provide APIs to third parties, e.g. budget planners

- unified drone legislation that allows me without tons of paperwork and individual permits to fly my drone everywhere reasonable in Europe