Trapping removes the animals that are in your building today. It does nothing about the hole they used to get in. That distinction is the single biggest reason people end up paying for the same job twice.
Why a removed animal gets replaced
An attic that has held squirrels smells like squirrels. Scent marking, urine and nesting material advertise the space to every animal that passes, and the entry point is still open.
Wildlife territory does not stay vacant. Remove a raccoon from a chimney in spring and, if the flue is still uncapped, there is a reasonable chance another one is in there within the season.
This is why the company that only sets traps can honestly say the problem was solved, and you can honestly say it came back. Both are true.
What exclusion actually means
A survey of the whole building envelope, not just the area where noise was heard. Roof returns, soffit and fascia joints, gable and ridge vents, chimney, roof-wall intersections, crawl space vents, foundation gaps and utility penetrations.
Each viable point is closed with material appropriate to the species. Hardware cloth behind a vent, metal flashing at a chewed fascia, a proper chimney cap rather than a screen laid over the flue.
Points that are still in use get a one-way door so the animal can leave but not return. Those come off and get sealed once activity has stopped.
Order of operations
Inspect, then remove, then seal, then clean. Sealing before removal traps animals inside. Cleaning before sealing means doing it twice.
The one exception is preventive exclusion on a building with no current activity, which is the cheapest version of this work by a wide margin.
What it costs relative to doing nothing
A preventive exclusion is a fraction of the cost of removal plus attic restoration after a season of occupancy. Contaminated insulation removal and replacement is frequently the largest single line on a wildlife invoice.
Chewed wiring is the other one. Squirrels and rats gnaw electrical insulation, and the repair is an electrician's bill on top of everything else.
Questions worth asking any company
Is sealing included in this quote, or is it a separate sale afterwards? How many entry points did you find, and can I see photographs of them? Is the sealing work warrantied, and for how long? What happens if something gets in through a point you closed?
A company that cannot answer those clearly is quoting you for trapping and calling it removal.