There are many LDS Scouting units that have non-LDS members. However, LDS Scouting is a different program than traditional Boy Scouts of America Scouting. The LDS Church was the first institutional sponsor of Boy Scouting. Under the terms of its 1913 agreement with the Boy Scouts of America and subsequent agreements, the LDS Church is permitted to make changes to the traditional Scouting program.
Here's a copy of the LDS "Green Book" (although not the current version, because I don't have a current link) on LDS Scouting. You'll see that the purpose of Scouting is to supplement the purposes of Aaronic Priesthood quorums and LDS Primary classes. Youth leaders are selected by the bishopric, not the youth. The responsibility for training adult Scouters falls upon the bishopric, not the BSA. Traditional Boy Scouting is designed to exist only until the youth are fourteen (not eighteen), and at fifteen, the youth move into Varsity Scouting (a national program, but it exists almost exclusively for the purposes of LDS Scouting). There is significantly less camping experience in LDS Scouting
I'm a former Council Commissioner of one of the nation's largest BSA Councils, and I work in national and regional roles.
It's simply a different program. Although there are special relationships for some groups, such as Catholic Scouting, nothing comes close to the fact that the BSA maintains a separate LDS-BSA relationship.
I could discuss the issue at length. There are excellent LDS Scout units. There are excellent LDS Scout leaders. LDS Scouting is simply a different program than traditional BSA Scouting.