There is nothing about Nosql databases that force you to have eventual consistency or lack Transactions. As far as forcing the correct schema, if you are using a statically typed language, it can enforce a “schema”. For instance with C#, LINQ and the standard Mongo driver, you work with strongly typed MongoCollection<T> and perform LINQ queries with IMongoQueryable<T>.

Amazon’s DynamoDB for instance supports transactions and optionally consistent reads. With Mongo you can set your WriteConcern to force strong consistency. Mongo also supports transactions.