I'm a history teacher in the Netherlands, mostly teaching teens from the age of 12 to 16 on a pre-academic/university kind of level.

I think history can be very romanticized and simplified on this level mostly because of two reasons. Firstly, time. There's a lot of history to go trough (in the first year of high school we go from the hunter-gatherer society until the high middle ages) and there is often little time to delve into the matter on a deeper level than what we conceive as historic facts. Secondly, the way teens are able to comprehend and appreciate history on a deeper level is limited. The notion that history is an ongoing discussion is not a concept they are often aware of.

That being said, I think that simplifying history should not be as prevelant as the examples you described. We try our best to teach kids that history is rarely black and white, and to always be aware of what sources their information came from.

More and more schools are teaching less sanitized history, particularly on Native Americans and slavery. I teach in a very diverse place in California and we are encouraged to spend more time on history of women and minorities and focus on actively analyzing history instead of spoonfeeding history, even on elementary age children (and I would feel that I'm doing a disservice to my mostly minority students if I don't teach them their own history).

The Thomas Edison issue is how much in-depth you can teach within a very limited amount of time and student attention span. We have to cover a large range of topics within the school year and sadly certain things will have to be left out. In addition you have to cater to every students, particularly at lower grade levels where all kids attend the same class. I would love to teach history in depth but it would not be a productive learning environment if only two history buff kids in class are interested while most students are bored to death by the same topic. In high school AP history classes the teachers can have a lot more interest and attention span to teach history more in-depth.

If anything, my education was the reverse of this romanticized view, focusing on faults to the exclusion of the positive, but I believe the issues I experienced apply to both issues.

In addition to concerns of patriotism and limits on teaching time (both major contributors to this problem) the history we teach in secondary school, in my experience, is usually fifty or more years out of date with historical scholarship. Of the noticeable historiographic influences in my education, for example, the newest was from the 1960s or early 1970s. We were frequently taught from these earlier schools which, as a general rule, lack the nuance of many newer historiographic schools.

I believe this problem is partly because of poor teaching (and sometimes students) at the collegiate level and partly because of how the secondary teaching profession usually works in the United States. Teachers are frequently assigned classes far out of their competence (a student with an English degree night teach history or vice versa) and are furthermore given poor texts to provide knowledge for themselves and their students. I believe that if teachers were treated as less interchangeable, there would be an immediate substantial improvement.

But to fully "fix" the issue, we also need to provide better historical training during bachelor's programs, choose better textbooks which utilize recent scholarship, and improve curriculums.

Even in uni-level courses, we're still leaving out a lot due to time. My aim is always to provide a balanced view of controversial people and events, but it can be impossible to offer the whole story. That's why libraries are filled with these huge tomes on nitpicky little topics. Just discussing Edison, for example, would necessitate a discussion of his rivalry with Tesla, as you suggested. Now, to be thorough, lectures should then be expanded to include the wives, lovers, and even assistants who came up with improvements to the experiments (in order to rectify the long trend of ignoring others' contributions to major discoveries), which would then require additional examination of these contributors' lives, and so on exponentially. The hardest part of developing survey-level lectures is deciding how far to go, what to keep or pass over, and stay focused on the goals of the course.