The LDS church uses donations from members to run the church and to provide welfare and humanitarian services for LDS and non-LDS throughout the world. When a member makes a donation to the Church, they can specify if its for tithing, fast offering, humanitarian, missionary work, perpetual education fund, etc. The Church uses the money as specified. The tithing dollars cover the construction of temples, churches, universities, etc. My understanding is that some of the tithing dollars go to wefare, but I'm not sure how much.
IMO the LDS Church does not claim that all donations cover welfare and humanitarian efforts. Charity is a very important mission of the LDS Church, but it also has a mission to spread the gospel and provide temple ordinances to people throughout the world. This necessitates funding.
Regardless of how much my church spends on the temples, churches, etc., it is also very generous with weflare and humanitarian efforts. Members of the Church are free to donate as much as they wish to these specific funds. Cattle ranches owned and operated by my church provide food for the "Bishop's Storehouse" which is a place that the poor can go to get free food, as directed by the local bishop. Most objective people see a marvelous thing in the LDS bishop's storehouse.
I realize that if I stopped paying my tithing and gave that 10% to charity, I would be giving more to charity than I give now. However, I consider it personally important to contribute money to the overall mission of my church which includes temple and church construction, etc.