There are many (many) reasons - so I'll list a few of the ones that I can think of off-hand.Here in the U.S. - we have a multi-party system: Provider-Payer-Patient (unlike other countries that have either a single payer - or universal coverage - or both). Given all the competing interests - at various times - incentives are often mis-aligned around the sharing of actual patient dataThose mis-aligned incentives have not, historically, focused on patient-centered solutions.  That's starting to change - but slowly - and only fairly recently.Small practices are the proverbial last mile in healthcare - so many are still paper basedThere are still tens/hundreds of thousands of small practices (1-9 docs) - and a lot of healthcare is still delivered through the small practice demographicThere are many types of specialties - and practice types - and they have different needs around patient data (an optometrist's needs are different from a dentist - which is different from a cardiologist)Both sides of the equation - doctors and patients - are very mobile (we move, change employers - doctors move, change practices) - and there is no centralized data store with each persons digitized health information.As we move and age - and unless we have a chronic condition - our health data can become relatively obsolete - fairly quickly (lab results from a year ago are of limited use today)Most of us (in terms of the population as a whole) are only infrequent users of the healthcare system more broadly (cold, flu, stomach, UTI etc....). In other words, we're pretty healthy, so issues around healthcare (and it's use) is a lower priorityThere is a signNow loss of productivity when a practice moves from paper to electronic health records (thus the government stimulus funding - which is working - but still a long way to go)The penalties for PHI data bsignNow under HIPAA are signNow - so there has been a reluctance/fear to rely on electronic data.  This is also why the vast majority of data bsignNowes are paper-based (typically USPS)This is why solutions like Google Health - and Revolution Health before them - failed - and closed completely (as in please remove your data - the service will no longer be available)All of which are contributing factors to why the U.S. Healthcare System looks like this:===============Chart Source: Mary Meeker - USA, Inc. (2011) - link here:http://www.kpcb.com/insights/usa...