As per my analysis block size and time limits create a bottleneck for the amount of bitcoin transactions that can be made at a given time. Nowadays, with increasing popularity and demand for bitcoins, there are transactions being created at a much faster speed than the network can process.Thousands of transactions waiting for an opportunity to enter into a block to be considered official or confirmed.
Miners are then free to choose which transactions they will include on the block. So they choose the transactions that pay higher fees. i.e. if you want your transaction to be processed quickly, you need to pay a fee that puts you in the top positions of that ranking. Transactions are competing against each other to see who can get there first.
And thats why the fees are so high.